Compact Torsional Spring Structure for Bi-Directional High Torque
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Solution Overview
Problem
Existing torsional springs for robotics face challenges such as low rigidity, difficulty in bi-directional response, unwanted contact, and increased complexity and bulk, particularly in wearable robotics where high torque transmission with minimal weight and dimensions is required.
Innovation Solution
A compact torsional spring design featuring a serpentine configuration with recesses and plate-like segments parallel to the torque axis, optimized for rigidity and torque transmission, which avoids unwanted contact and simplifies interfacing, using materials like steel, aluminum, or titanium alloys to achieve high rigidity and transmissible torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If wire helical torsional springs are used, then the actuator can transmit torque, but the rigidity is low with respect to robotic application requirements
Solution Approach 1:
The torsional spring is segmented into multiple plate-like segments arranged in parallel between the input and output flanges. Each segment contributes to the overall torsional stiffness, allowing the system to achieve high rigidity through the combined effect of multiple segments rather than relying on a single complex wire helical structure.
Solution Approach 2:
The invention transitions from a three-dimensional wire helical structure to a series of two-dimensional plate-like segments arranged in parallel. This dimensional change allows for more efficient torque transmission and higher rigidity with reduced complexity, as the plates can be directly loaded in tension and compression along their length.
2Adaptability or versatility
If wire helical torsional springs are used, then the actuator can provide elastic response, but bi-directionality is difficult to obtain without increasing complexity and mass
Solution Approach 1:
The plate-like segment structure serves multiple functions simultaneously: it provides torsional elasticity, enables bi-directional rotation, and maintains structural integrity. The parallel arrangement of plates naturally accommodates rotation in both directions without requiring separate spring mechanisms for each direction, thus achieving universality.
Solution Approach 2:
The invention merges the functions of multiple wire helical springs (which would be needed for bi-directional operation) into a single integrated structure of parallel plates. This combination eliminates the need for separate springs and complex coupling mechanisms, reducing overall device complexity while maintaining bi-directional capability.
3Reliability
If wire helical torsional springs are used, then the actuator can transmit torque, but contact between coils during motion causes unwanted contact and sliding
Solution Approach 1:
By segmenting the spring into discrete parallel plates, the invention eliminates the continuous coil structure that causes contact and sliding issues. Each plate operates independently without contacting adjacent plates during torsional motion, thereby eliminating the harmful contact and sliding effects present in wire helical springs.
4Ease of operation
If machined helical torsional springs are used, then interfacing capability is improved, but the preferential direction of rotation limits bi-directional application
Solution Approach 1:
The parallel plate structure with flanges provides universal interfacing capability while naturally accommodating rotation in both directions. The plates are arranged symmetrically about the axis of rotation, allowing equal performance in clockwise and counter-clockwise directions, thus achieving versatility without compromising interfacing capability.
5Strength
If spiral torsional springs are used, then some drawbacks of wire springs are overcome, but two-directional response still requires multiple springs increasing complexity
Solution Approach 1:
The invention merges multiple plate segments into a single integrated torsional spring assembly that achieves the desired rigidity through the parallel arrangement of plates. This unified structure eliminates the need for multiple separate spiral springs, reducing device complexity while maintaining or improving torsional rigidity.
6Adaptability or versatility
If linear springs with conversion mechanism are used, then two-directional response is achieved, but overall dimension becomes large
Solution Approach 1:
The invention adopts a planar arrangement of parallel plates that efficiently utilizes the available space between the input and output flanges. This two-dimensional plate configuration achieves bi-directional response without requiring the large three-dimensional volume needed for conventional linear spring conversion mechanisms, thus reducing overall actuator dimensions.
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 design provides a robust, lightweight torsional spring with a linear angle/torque characteristic, capable of transmitting high torques relative to its weight and dimensions, while avoiding contact issues and simplifying interfacing, making it suitable for wearable robotics and other applications requiring high torque and rigidity.
Implementation Method 1
A torsional spring according to the present invention, in which a metal element, due to suitable machining, takes the shape of a body (1) having recesses (2, 3) mainly developing according to planes (A) parallel to an axis (X) representing the centre axis of the torque
Data Source
AI summary
A torsional spring that can be used as a joint adapted to transmit at torsion actuation with elastic response. The torsional spring relates to a compact torsional elastic element, provided with a linear torque characteristic which is also not affected by the direction of rotation. The torsional spring is capable of attaining a high transmissible torque relative to its weight and overall dimension.