Variable Ratio Gearing for Sliding Door Damping Control
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Solution Overview
Problem
Existing movement control devices for sliding doors often fail to provide a balanced damping force, leading to rebound issues when doors are closed forcefully, as they either provide too little resistance initially or too much resistance throughout the closing motion.
Innovation Solution
A damped movement control device with a gearing mechanism that includes a first pinion and racks, where the pinion is engaged with both racks, allowing for a differential movement that reduces initial damping resistance and increases it towards the end of the door's travel, using a combination of a tension spring and a linear piston and cylinder damper to assist and resist the door's closing movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant damping force is applied throughout the door closing motion, then the door can be controlled to close smoothly, but the door will rebound when closed forcefully due to excessive resistance at the end of travel
Solution Approach 1:
The patent applies the dynamics principle by making the damping force variable rather than constant. The gearing mechanism with variable ratio dynamically adjusts the damping force throughout the door closing motion - providing lower damping during initial travel and higher damping near the end of travel. This resolves the contradiction by adapting the damping characteristic to the specific requirements at different stages of the closing motion, preventing rebound while maintaining smooth closure control.
Solution Approach 2:
The patent employs parameter changes by varying the damping force parameter throughout the door closing cycle. The variable ratio gearing mechanism changes the effective damping parameter from a constant value to a varying value that increases as the door approaches its closed position. This parameter transformation allows the system to provide appropriate resistance at each stage of motion, solving the rebound problem caused by constant high resistance.
2Reliability
If high damping resistance is provided throughout the closing motion to prevent rebound, then door closure control improves, but the initial closing motion becomes overly resistant and unnatural
Solution Approach 1:
The variable ratio gearing mechanism dynamically adjusts the damping characteristic to match the natural closing motion requirements. During initial door travel, the gearing provides a lower damping ratio allowing smooth, natural closing. As the door approaches closure, the ratio increases to provide higher damping for rebound prevention. This dynamic adaptation resolves the contradiction between rebound prevention and smooth operation.
Solution Approach 2:
The patent applies local quality by providing different damping characteristics for different portions of the door travel. The initial portion of travel receives low damping for smooth operation, while the final portion receives high damping for rebound prevention. This spatial variation in damping quality resolves the contradiction by optimizing the damping characteristic for each local requirement along the door's path of motion.
3Device complexity
If a simple gearing mechanism is used to convert door movement, then device complexity is reduced, but the ability to provide variable damping rates is insufficient
Solution Approach 1:
The patent introduces an intermediary variable ratio gearing mechanism that mediates between the door movement and the damper actuation. This intermediary mechanism converts the single-degree-of-freedom door motion into differential actuation of the damper, enabling variable damping rates without requiring complex control systems. The gearing acts as a mechanical mediator that provides adaptability through its variable ratio characteristics.
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 achieves a two-stage damping effect, providing a 'soft' initial resistance to prevent rebound and a 'hard' final resistance to absorb high forces, ensuring smooth door closure and robust operation with adjustable damping characteristics.
Implementation Method 1
a linear piston and cylinder type damper (12)... the slider (27) is constrained to move when the actuator assembly (13) moves, through the interengagement of the pinion (24) and the two racks (25, 26)... causing its compression. Thus, the closing movement of the door is both assisted by the pulling action of the spring (11) and also resisted by the damping action of the damper (12)
Implementation Method 2
The spring (11) provides the force to the door and the damper (12) provides the damping... One end of the spring (11) is anchored to the carriage (14), with the other end being anchored to the housing (10)... the actuator assembly (13) to be pulled towards its other end position under the tensile force of the spring (11)
Implementation Method 3
The mechanism (23) comprises a pinion (24) which is sandwiched between and in toothed engagement with a first rack (25) on the carriage (14) and a second rack (26) arranged in parallel on the housing (10)... The slider (27) engages the free end of the piston rod (28) of the damper (12)... the slider (27) is constrained to move when the actuator assembly (13) moves, through the interengagement of the pinion (24) and the two racks (25, 26)
Data Source
Figure 1~2
AI summary
A device is provided for controlling the closing movement of a sliding door. The device comprises a housing (10) containing a spring (11) which is actuable to provide a pulling force to the closing movement of the door. The housing (10) also contains a damper (12) which is actuable to impart a damped resistive force to the closing movement of the door. Incorporated within the device is a gearing mechanism for converting the rate of the closing movement of the door into two or more rates of actuation of the damper over at least part of the door's travel.