Variable Force Brake for Cordless Window Coverings
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Solution Overview
Problem
Existing cordless window covering systems face challenges in balancing the load of window panels due to varying forces exerted by spring motors, brakes, and system friction, limiting their use to custom blinds and increasing costs, while size-in-store window coverings require easier and more cost-effective balancing solutions.
Innovation Solution
An operating system comprising a spring motor, variable force brake, and lift spool assembly, with a synchronized effective shaft, utilizes a one-way clutch and adjustable brake mechanism to balance the panel load, allowing for size-in-store window coverings and reducing costs by optimizing motor force and brake force distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant force brake is used in cordless window covering systems, then the system can provide stable braking force, but the brake force cannot be optimized to match varying panel load conditions, limiting application to custom blinds and increasing costs
Solution Approach 1:
The brake system transitions from a constant force mechanism to a dynamic variable force brake that automatically adjusts braking force based on panel position. The cam mechanism converts rotational motion into variable linear force, creating a dynamic braking system that adapts to changing load conditions throughout the panel's travel range.
Solution Approach 2:
The braking force parameter is changed from constant to variable by introducing a cam mechanism with a specifically shaped cam surface. The cam profile varies the distance between the cam follower and cam center, thereby varying the braking force applied to the brake shoe according to panel position, optimizing performance across different load conditions.
2Reliability
If custom blind systems are used with optimized braking, then load balancing can be achieved, but the complexity and cost increase, making size-in-store window coverings less viable
Solution Approach 1:
The variable force brake mechanism serves multiple functions: it provides braking force, automatically adjusts to varying panel loads, and enables both custom and size-in-store window covering applications. The cam mechanism simultaneously controls brake shoe engagement and provides load-adaptive braking without requiring separate adjustment mechanisms for different applications.
Solution Approach 2:
The brake system automatically self-adjusts to varying panel loads through the cam mechanism without requiring external control or manual adjustment. As the panel moves through its range of motion, the cam profile automatically varies the braking force to match the changing load conditions, eliminating the need for complex control systems or manual calibration.
3Force
If brake force is increased to handle maximum panel load, then the system can support heavier panels, but the brake force becomes excessive for lighter panels, causing difficulty in operation
Solution Approach 1:
The braking force parameter is dynamically changed throughout the panel's travel range using the cam mechanism. When the panel is in positions requiring maximum support (fully raised), the cam profile maximizes brake shoe engagement. When the panel is in positions requiring less force (partially lowered), the cam profile automatically reduces braking force, maintaining ease of operation across all positions.
Solution Approach 2:
The cam mechanism preemptively adjusts braking force based on anticipated panel position and load conditions. As the panel approaches positions where maximum braking force is needed, the cam profile progressively increases brake engagement, ensuring optimal braking force is available when needed without applying excessive force during lighter load conditions.
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 effectively balances window panel loads, enabling use in size-in-store window coverings and reducing costs by optimizing motor force and brake force distribution, providing a more efficient and cost-effective solution for cordless window covering operations.
Implementation Method 1
The operating system comprises a spring motor, a variable force brake, and a lift spool assembly
Implementation Method 2
The variable force brake comprises an outer race selectively coupled for rotation with the shaft by a one-way clutch where the outer race of the brake is in contact with a brake member such that the braking force applied by the brake member to the outer race varies as the panel is raised and lowered
Implementation Method 3
The one-way clutch may comprise a one-way needle bearing comprising a plurality of needle bearings that receive the effective shaft where the one-way needle bearing is mounted for rotation with the outer race
Data Source
AI summary
An operating system for a window covering includes at least one spring motor, at least one variable force brake, and at least one lift spool assembly operatively coupled to a panel for raising and lowering a panel. An effective shaft is operatively coupled to and synchronizes the spring motor, the variable force brake, and the lift spool. The variable force brake comprises a one-way clutch operatively coupled to the shaft. A brake member is operatively engaged with the one-way clutch to apply a brake force to the one-way clutch when the shaft is rotated. The magnitude of the brake force applied to the one-way clutch is determined by the rotational position of the shaft.