Nested Torsional Damper for Electric Machine Driveline
Solution Overview
Problem
The installation of an electric generator in the driveline of ground vehicles increases torsional stresses on the engine crank shaft, leading to potential failure, and existing torsional dampers are not compact enough to effectively mitigate these stresses while maintaining driveline efficiency.
Innovation Solution
A compact torsional damper design featuring a plurality of radially adjacent shaft segments with slots to increase torsional compliance, connected via end segments, which are operatively connected to the generator shaft and flywheel, allowing for deformation and reduced stress transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional long shaft torsional damper is installed between the generator and engine flywheel to reduce torsional stresses, then the crank shaft durability is improved, but the overall length of the driveline installation increases
Solution Approach 1:
The patent implements a nested torsional damper structure where multiple shaft segments (first shaft segment, second shaft segment, third shaft segment) are arranged concentrically around each other. The first shaft segment is nested within the second shaft segment, which is nested within the third shaft segment, allowing the dampener to achieve the required torsional compliance in a compact radial arrangement rather than requiring a long axial shaft
Solution Approach 2:
The torsional damper is divided into multiple discrete shaft segments (first, second, and third shaft segments) connected by end segments. Each shaft segment includes slots that allow independent deformation, enabling the distributed torsional compliance to be achieved through radial stacking of segments rather than a single long shaft
2Reliability
If a torsional damper is installed to smooth torque fluctuations and protect the crank shaft, then the driveline reliability is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple functional elements into a unified nested structure. The shaft segments, end segments, and slots work together as an integrated torsional compliance system, merging the functions of stress absorption, torque smoothing, and mechanical coupling into a single compact assembly rather than requiring separate components
Solution Approach 2:
The slots are strategically positioned in each shaft segment to create localized areas of compliance. The end segments connect the shaft segments at specific locations, allowing the torsional flexibility to be distributed at precise points where it is most needed to absorb crank shaft stresses while maintaining overall structural integrity
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 compact torsional damper design effectively reduces torsional stresses on the crank shaft, enhancing the durability of the driveline components and maintaining efficient power transmission by increasing torsional compliance and dampening capabilities.
Implementation Method 1
each of the plurality of shaft segments including a plurality of shaft slots extending through a wall thereof to increase torsional compliance of the plurality of shaft segments
Implementation Method 2
The compact torsional damper design effectively reduces torsional stresses on the crank shaft, enhancing the durability of the driveline components
Data Source
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AI summary
A damper for an electric machine (10) includes a shaft (20) and at least one shaft segment (26) concentric about the shaft (20) and operably connected to the shaft (20). The at least one shaft segment (26) includes a plurality of shaft slots (38) extending through a wall (40) of the at least one shaft segment (26) to increase torsional compliance of the at least one shaft segment (26). A driveline mounted electric machine (10) includes at least one rotor (16) located at a central axis (18) of the electric machine (10) and a damper. The damper includes a shaft (20) in operable communication with the at least one rotor (16) and at least one shaft segment (26) concentric about the shaft (20) an operably connected thereto. The at least one shaft segment (26) includes a plurality of shaft slots (38) extending through a wall (40) of the at least one shaft segment (26) to increase torsional compliance of the at least one shaft segment (26).