Compact Control System for Architectural Coverings
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Solution Overview
Problem
Existing control systems for retractable architectural coverings require a large outer diameter due to the engagement mechanism between the spider and ring gear, making them unsuitable for confined spaces like head rails in window coverings other than roller blinds.
Innovation Solution
A control unit with a shift arm rotationally supported about an axis parallel to the input member, allowing engagement and disengagement with the planet carrier to control its rotation, combined with a helical track and switch ring for axial engagement with the ring gear, enabling the same rotational direction for both the planet carrier and ring gear, and an automatic brake mechanism using a wrap spring for secure positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a spider engagement mechanism is used between the planet carrier and ring gear, then the transmission can achieve reversible rotation directions, but the outer diameter of the transmission becomes relatively large
Solution Approach 1:
The patent extracts the spider component from the transmission system and replaces it with a shift arm mechanism. The shift arm selectively engages the planet carrier to control rotation direction without requiring the spider's complex leg structure that would increase the outer diameter. This extraction of the problematic component directly resolves the contradiction between operational versatility and compact size.
Solution Approach 2:
Instead of using the spider to engage the ring gear internally (which requires the ring gear to surround the planet carrier), the invention inverts the approach by using the shift arm to engage the planet carrier from the outside. This inversion of the engagement mechanism allows for a more compact transmission design with reduced outer diameter while maintaining the ability to control rotation directions.
2Adaptability or versatility
If the ring gear surrounds the planet carrier to accommodate spider engagement, then reversible rotation is enabled, but the space required in the head rail increases
Solution Approach 1:
The spider component is extracted and removed from the system, replacing it with a more space-efficient shift arm mechanism. This extraction eliminates the need for the ring gear to surround the planet carrier, thereby reducing the volume required in the head rail while preserving the reversible rotation capability through alternative means.
Solution Approach 2:
The patent changes the dimensional arrangement of the engagement mechanism. Instead of radial engagement where the ring gear surrounds the planet carrier (requiring large volume), the shift arm engages the planet carrier in a different dimensional configuration that reduces the space required in the head rail while achieving the same functional outcome of reversible rotation.
3Volume of moving object
If a compact transmission design is used to fit limited spaces, then space efficiency improves, but the complexity of the control mechanism increases
Solution Approach 1:
The control mechanism is segmented into distinct functional components: the shift arm for direction control, the brake mechanism for positioning, and the planetary gear set for motion transmission. This segmentation allows each component to be optimized independently for compactness while maintaining overall system simplicity. The shift arm specifically is designed as a simple lever that pivots between two positions, avoiding complex control mechanisms.
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 allows for a compact control system that fits within limited spaces, providing ergonomic operation with a single operating element for both raising and lowering the covering, while ensuring child safety and efficient assembly.
Implementation Method 1
a wrap spring (81) which is effective to apply friction to a drum (30) to hold the covering in position
Implementation Method 2
a spring motor in the spool retracts the cord
Data Source
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AI summary
A control unit for rotationally driving, in a selected one of rotationally opposite directions, a mechanism for moving a covering for an architectural opening. The covering may be moved between extended and retracted positions. The control unit includes: a housing, a single operating element that enables operation by manually imparting a repetitive linear motion thereto, and a rotational input member for engagement by the single operating element. The input member being journalled with respect to a cylindrical cavity in the housing for rotation between first and second rotational end positions. A return mechanism returns the rotational input member from the second end position back to the first rotational end position. A sun gear is driven by the first rotational element and engages a planet carrier through a plurality of planet gears. A ring gear is engaged by the planet gears can be coupled to the planet carrier for rotation therewith and the planet carrier can be held stationary to cause the ring gear to rotate in an opposite direction to first rotational element. A rotational output member is adapted to be driven by the ring gear or to be kept stationary by a brake mechanism acting between the output member and the housing. A switch ring is operative in translating rotation of the sun gear in rotation of the ring gear in one or the other direction with respect to rotation of the sun gear. The direction of rotation is dictated by selective operation of the single operating element in a first position of angular deflection or in a second position of angular deflection. A covering for an architectural opening including at least one covering that is retractable and extendible by a mechanism for moving the at least one covering member between extended and retracted positions and provided with such a control unit is also disclosed.