Window Sash Security Device with Plastic Deformation Energy Absorption
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Solution Overview
Problem
Existing security devices for window or door sashes, which rely on a rope to absorb kinetic energy in case of a sash detachment, may fail to effectively manage high kinetic energy generated by heavy sashes during extreme events, leading to potential damage.
Innovation Solution
A safety device with an end piece and deformation area that maintain continuous contact along a movement axis, ensuring continuous energy absorption without intermediate increases, and providing anti-twist protection to the rope, allowing it to transmit higher tensile forces by only being subjected to tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cable is used to secure the sash to the frame, then the sash can be held in place during normal operation, but the cable cannot effectively absorb kinetic energy when the sash detaches
Solution Approach 1:
The energy absorption device is divided into multiple deformable ribs arranged in a stepped configuration, where each rib segment absorbs kinetic energy through controlled deformation. This segmentation allows progressive energy absorption throughout the sash's movement range, preventing sudden energy spikes that would compromise cable integrity.
Solution Approach 2:
The deformable ribs are pre-configured in a compressed state within the energy absorption device, ready to deform and absorb kinetic energy before the sash actually detaches. This beforehand cushioning mechanism ensures that when detachment occurs, the energy is absorbed continuously without causing sudden cable tension spikes.
2Loss of energy
If the deformation area is made larger to absorb more kinetic energy, then energy absorption capacity increases, but the device complexity and size increase
Solution Approach 1:
The deformable ribs are strategically positioned at specific locations within the energy absorption device, with varying thicknesses and heights optimized for local energy absorption. This local quality approach concentrates energy absorption capability where needed most, avoiding unnecessary material and complexity in regions where energy absorption is not required.
Solution Approach 2:
The energy absorption device utilizes changes in geometric parameters (rib thickness, height, spacing) to optimize energy absorption capacity. By adjusting these parameters rather than simply increasing overall device size, the patent achieves high energy absorption capacity with minimal complexity and compact dimensions.
3Ease of operation
If the cable is allowed to rotate during sash movement, then the cable can accommodate movement more freely, but the cable is subjected to torsional stress that reduces its tensile strength
Solution Approach 1:
A guide pulley is introduced as an intermediary component between the cable and the sash, which allows the cable to move freely during normal operation while preventing rotational movement. The guide pulley mediates between the need for movement freedom and the need to maintain cable tensile strength by converting rotational motion into guided linear motion.
Solution Approach 2:
Instead of allowing the cable to rotate freely to accommodate movement, the invention inverts the approach by constraining the cable to non-rotating movement and using the guide pulley to accommodate the sash's movement. This inversion maintains cable integrity while still enabling operational freedom.
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 solution enables effective kinetic energy reduction, allowing for the use of smaller and simpler components, and prevents sudden maximum tensile forces on the rope, ensuring safer and more reliable energy dissipation during sash movement.
Implementation Method 1
the end piece plastically deforms the deformation area to absorb the kinetic energy
Data Source
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AI summary
The invention relates to a locking device (20) for a sash (14) of a window or door assembly (10), in which the sash is mounted on the frame so as to be movable about at least one axis (16) within a defined movement range, wherein the locking device comprises: a first fitting (22) for connection to the frame, a second fitting (24) for connection to the sash, a cable (26) which is connected to the first fitting and to the second fitting and is only effective for transferring the weight of the sash to the frame and securing the sash to the frame when the sash is positioned outside the defined movement range, and an energy absorption device (28) for absorbing kinetic energy of the sash, wherein the energy absorption device has an end piece associated with the cable and a deformation area associated with one of the fittings.wherein - when the wing is arranged outside the intended movement space - the end piece plastically deforms the deformation area to absorb the kinetic energy, wherein the end piece and the deformation area are continuously in contact with each other along a movement axis of the end piece and secured against free relative rotation about the movement axis, so that energy can be dissipated continuously along the movement axis without an intermediate increase in the kinetic energy of the wing.