Anisotropic Breakaway Shaft Element for Directional Torque Limiting
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Solution Overview
Problem
Conventional shafts in mechanical engineering and vehicle construction lack the ability to differentiate between torsional moments in opposite directions, leading to inadequate torque transmission control in electric vehicles, where higher torque is required during driving but lower torque is needed during recuperation to avoid damage.
Innovation Solution
A predetermined breaking body with anisotropic properties, featuring a fiber-reinforced material structure or metallic material with helical recesses, allows for distinct ultimate torsional moments in different torsion directions, enabling controlled torque transmission by yielding under specific tensile or compressive loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional isotropic shaft is used, then the shaft yields under the same ultimate moment in both torsion directions, but this prevents differentiated torque transmission control needed for motorized mode (high torque) versus generator mode (low torque)
Solution Approach 1:
The shaft incorporates an anisotropic material structure with helical reinforcement elements arranged at a specific angle (e.g., 45 degrees) to the shaft axis. This asymmetric arrangement causes the shaft to exhibit different ultimate torsional moments for opposite torsion directions: one direction engages the reinforcement elements in tension while the other engages them in compression, enabling differentiated torque transmission for motorized versus generator modes
Solution Approach 2:
The invention changes the material parameters of the shaft by using anisotropic materials with direction-dependent mechanical properties. The reinforcement elements are oriented at specific angles to create different stiffness and strength characteristics for clockwise versus counter-clockwise torsion, allowing the shaft to transmit higher torque in motorized mode while limiting torque in generator mode
2Reliability
If the shaft is designed to transmit high torque in motorized mode, then reliable torque transmission is achieved, but the shaft may transmit excessive torque in generator mode causing damage to the electric machine
Solution Approach 1:
The anisotropic shaft structure with helical reinforcement at specific angles creates inherent asymmetry in torque transmission capability. When torque is applied in motorized mode, the reinforcement elements are optimally engaged to transmit high torque reliably. When torque is applied in generator mode, the same structural asymmetry causes the shaft to yield at a lower ultimate moment, preventing excessive torque from reaching the electric machine and causing damage
3Adaptability or versatility
If an anisotropic material structure with helical reinforcement is used, then differentiated ultimate torsional moments in opposite torsion directions are achieved, but the manufacturing complexity increases
Solution Approach 1:
The shaft is constructed as a composite structure combining a base material (e.g., metal or polymer) with reinforcement elements (e.g., fibers, wires, or ribs) arranged in a helical pattern. This composite approach enables the anisotropic mechanical properties needed for differentiated torque transmission while using well-established composite manufacturing techniques to manage production complexity
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 ensures reliable torque transmission in motorized mode while preventing excessive torque in generator mode, enhancing the operational efficiency and safety of electric vehicles by predetermining yield points based on torsion direction.
Implementation Method 1
The predetermined breaking element (6), for example a material of the predetermined breaking element, is anisotropic, as a result of which, during the transmission of a torque between the sub-bodies (4, 5), the predetermined breaking element (6) and, consequently, the predetermined breaking body (1) yield in a first torsion direction (D1) under a first predetermined ultimate torsional moment (M1) and yield in a second torsion direction (D2) opposed to the first torsion direction (D1) under a second predetermined ultimate torsional moment (M2)
Data Source
AI summary
Please substitute the new Abstract submitted herewith for the original Abstract: A predetermined breaking body of a shaft of a machine includes a first sub-body, a second sub-body, and a predetermined breaking element. The first and second sub-bodies are connected to one another, so as to conjointly rotate, along a longitudinal center axis of the predetermined breaking body via the predetermined breaking element. The predetermined breaking element is anisotropic, such that during transmission of a torque between the sub-bodies, the predetermined breaking element yields in a first torsion direction under a first predetermined ultimate torsional moment and yields in a second torsion direction opposed to the first torsion direction under a second predetermined ultimate torsional moment. The predetermined ultimate torsional moments differ in size.