Handle Set Engagement Cartridge for Consistent Return Torque
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Solution Overview
Problem
Existing door latches with spring-biased mechanisms provide inconsistent torque resistance, making it difficult for users with low strength, such as the elderly or those with disabilities, to operate the handles effectively.
Innovation Solution
A door actuator assembly with a spring assembly that includes a gear, rack, and sliders, which applies a consistent spring force to return the handle to a default position, allowing controlled torque resistance and automatic resetting regardless of rotation direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a coiled spring is used to return the handle to the default position, then the handle can be returned automatically, but the torque resistance is inconsistent and cannot be adjusted for users with limited strength
Solution Approach 1:
The patent changes the spring configuration from a single coiled spring to multiple springs arranged in a star pattern around the actuator shaft. This parameter change allows for consistent torque resistance in all rotational directions and enables adjustment of the total spring force by changing the number, stiffness, or pre-compression of individual springs, making it suitable for users with varying strength requirements.
Solution Approach 2:
The patent segments the single spring function into multiple identical springs distributed symmetrically around the actuator shaft. Each spring contributes equally to the total torque, providing consistent resistance regardless of rotation direction. This segmentation also allows independent adjustment of each spring's properties to achieve desired total torque characteristics.
2Device complexity
If a coiled spring is positioned axially aligned with the actuator, then the structure is simple, but the torque resistance varies with rotation direction
Solution Approach 1:
The patent uses symmetric arrangement of multiple springs around the actuator shaft rather than axial alignment. This symmetric (not asymmetric) configuration ensures that the torque resistance is identical in all rotational directions, eliminating the direction-dependent variation present in axial spring arrangements while maintaining structural simplicity through the regular geometric pattern.
Solution Approach 2:
The patent transitions from a one-dimensional axial spring arrangement to a two-dimensional radial arrangement of springs around the actuator shaft. This dimensional change allows the springs to be positioned at different angular locations while maintaining equal radial distance from the shaft, providing consistent torque in all directions without significantly increasing structural complexity.
3Reliability
If the spring force is increased to provide stronger return force, then the handle returns more reliably, but it becomes difficult for users with limited strength to operate
Solution Approach 1:
The patent makes the spring system adjustable rather than fixed. The number of active springs, their individual stiffness, and their pre-compression can be modified to match the strength capabilities of different user groups. This dynamic adjustability allows optimization of the return force to be reliably strong enough while remaining operable by users with limited strength.
Solution Approach 2:
The patent enables parameter adjustment of the total spring force through multiple independent parameters: the number of springs in the assembly, the stiffness coefficient of each spring, and the pre-compression amount of each spring. By changing one or more of these parameters, the system can be tuned to provide appropriate return force for different application requirements and user capabilities.
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 provides a consistent and controlled user experience by ensuring the handle returns to a default position automatically, offering adjustable torque resistance suitable for various user needs, including those with limited strength.
Implementation Method 1
at least one spring positioned to apply a spring force to the rack toward the neutral position when the rack is in the displaced position
Data Source
AI summary
A spring assembly for a handle set assembly includes a housing and a gear rotatably positioned within the housing. The gear has a default position and at least one actuated rotated position. The spring assembly includes at least one rack positioned within the housing. The at least one rack is movable in a rack displacement direction that is normal to the axis of rotation of the gear in response to rotation of the gear between a neutral position and a displaced position. The spring assembly includes a slider positioned at a first end of the at least one rack, the slider being slidable along the rack displacement direction. The spring assembly includes at least one spring captured between the housing and slider. The at least one spring is positioned to apply a spring force to the at least one rack toward the neutral position when the at least one rack is in the displaced position.