Modulated Braking System for Roof Window Lifting Devices
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Solution Overview
Problem
Existing lifting devices for roof-mounted windows face challenges in providing consistent braking force across varying roof inclinations and window sash weights, leading to uneven operation and increased wear, with existing solutions either being inflexible or requiring frequent adjustment and replacement.
Innovation Solution
A lifting device with a modulated braking system that adjusts the braking force based on roof inclination and window sash weight, using a mechanism with inclined slide faces and multiple brake shoe segments to provide a progressive and proportional braking effect, allowing for easy adjustment without part replacement, and reducing wear and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant braking effect is added through a threaded bolt adjusting lateral brake shoes, then the window can be held firmly in near-closed positions, but the accumulated braking effect becomes larger than desired in positions of larger opening angles, making it too hard for users to move the window
Solution Approach 1:
The braking device transitions from a static constant braking effect to a dynamic path-dependent braking effect. The slide shoe's movement path through the guidance creates varying friction forces that automatically adjust the braking effect based on window position, providing strong braking when needed (near-closed) and reduced braking when moving (larger opening angles).
Solution Approach 2:
The braking force parameter changes dynamically with the slide shoe's position in the guidance. The friction force is modulated by the geometric relationship between the slide shoe and guidance during movement, creating a path-dependent braking effect that varies continuously with window opening angle rather than remaining constant.
2Reliability
If the braking device uses a linkage mechanism with brake members connected by an angled link, then path-dependent braking effect is achieved, but the device complexity increases and the mechanism requires more components
Solution Approach 1:
The complex linkage mechanism with multiple brake members and angled links is extracted and replaced by a simpler direct friction-based system. The essential path-dependent braking function is retained by using the slide shoe's movement through the guidance, eliminating the need for additional linkage components while maintaining the desired braking characteristics.
Solution Approach 2:
The guidance structure itself provides the braking function through friction with the slide shoe, rather than requiring a separate braking mechanism. The geometric relationship between the slide shoe path and guidance automatically generates the path-dependent braking effect, making the system self-regulating without additional active components.
3Ease of operation
If the slide shoe provides frictional braking force normal to the guidance bottom face, then the window can be positioned between fully opened and fully closed, but the braking effect varies with window position, being larger when opened and lower when near-closed
Solution Approach 1:
The varying friction force that initially causes inconsistent braking is converted into a beneficial path-dependent braking effect. By designing the slide shoe's movement path through the guidance, the friction force naturally provides stronger braking when the window is near-closed (when it's most needed) and weaker braking when the window is opened (when less braking is needed), turning a problem into a solution.
4Reliability
If the braking device is adjusted to provide sufficient braking in near-closed positions, then the window can be held firmly, but the accumulated braking effect is larger than desired in positions of larger opening angles
Solution Approach 1:
The braking force transitions from a static adjusted constant value to a dynamic value that automatically adapts to window position. The slide shoe's movement through the guidance creates varying normal forces and friction coefficients, resulting in a braking effect that is automatically optimized for each position without requiring manual adjustment for different operating 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 device ensures a consistent and adjustable braking force across different installation conditions, reducing the effort required to open and close the window and extending the device's lifespan by minimizing wear, while allowing for easy adaptation to changing conditions such as roof inclination and accessory installation.
Implementation Method 1
The slide shoe is biased by means of a spring arrangement
Implementation Method 2
During opening and closing of the window the slide shoe slides in the guidance, providing a frictional braking force normal to a guidance bottom face
Data Source
Figure 1
Figure 2~2b
Figure 3~3b
AI summary
The lifting device comprises abiased slide shoe adapted to be slidable with respect to a member of an openable structure, a lifting arm having two ends, one end adapted to be pivotally connected with a member of the structure and the other end associated with said slide shoe, and a braking device comprising at least one brake shoe slidable on a respective brake face of said lifting device, said braking device modulating the force resulting from the bias on said biased slide shoe. An adjusting device is adapted to adjust said progressive modulation of said force resulting from the bias on said biased slide shoe, and comprises a manipula- tion member, which when manipulated by a user activates said adjusting device to adjust a brake force of said brake shoe exerted on said brake face in a given position of said brake shoe.