Input Shaft Diameter Tuning for Quieter Vehicle Drive Gears
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Solution Overview
Problem
The existing vehicle drive devices experience torsional vibration issues between the rotor shaft and input gear, leading to increased noise due to dynamic stiffness at the gear meshing points, which is costly to mitigate by altering the torque transmission distance.
Innovation Solution
Incorporating a small diameter portion on the input shaft between the supported and connection portions reduces the torque transmission rigidity, shifting the resonance point of torsional vibration and minimizing noise transmission to the case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the torque transmission distance is changed to reduce torsional vibration frequency, then the noise can be reduced, but the layout of the vehicle drive device must be significantly changed or cost increases
Solution Approach 1:
The patent applies local quality by creating a small diameter portion at a specific location on the input shaft (between the first supported portion and connection portion). This localized structural modification changes the rigidity distribution along the input shaft, thereby adjusting the torsional vibration frequency without requiring overall layout changes. The small diameter portion serves as a targeted intervention point that modifies vibration characteristics while maintaining the rest of the device layout intact.
Solution Approach 2:
The patent changes the physical parameter of the input shaft by reducing its diameter in a specific section. This parameter change (diameter reduction) directly affects the rigidity and torsional characteristics of the shaft, shifting the resonance frequency to reduce noise. This approach allows parameter optimization without complex layout modifications or increased costs.
2Object-affected harmful factors
If the torque transmission distance is changed to reduce torsional vibration frequency, then the noise can be reduced, but cost increases
Solution Approach 1:
The localized small diameter portion on the input shaft provides a cost-effective solution by modifying only a specific section rather than requiring comprehensive redesign or material changes throughout the entire drive device. This targeted approach minimizes manufacturing complexity and cost while achieving the noise reduction objective.
Solution Approach 2:
Changing the diameter parameter of an existing component (input shaft) is more cost-effective than redesigning the entire torque transmission path. This parameter modification can be achieved through standard manufacturing processes without requiring expensive new components or assembly changes.
3Object-affected harmful factors
If the rigidity of the input shaft is reduced to shift resonance point, then vibration and noise are reduced, but the structural strength may be compromised
Solution Approach 1:
The small diameter portion is strategically positioned between the first supported portion and connection portion, creating a localized flexibility zone that does not compromise the overall structural strength. The supported portions and connection portions maintain their full diameter and strength, while only the intermediate section is reduced in diameter to adjust vibration characteristics.
Solution Approach 2:
The input shaft is effectively segmented into different functional zones: the first supported portion with full diameter for strength and support, the small diameter portion for vibration control, and the connection portion for torque transmission. This segmentation allows each section to optimize its function without compromising the others.
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 configuration effectively reduces vibration and noise by adjusting the rigidity of the input shaft without significant changes in layout or cost, providing a simple and cost-effective solution.
Implementation Method 1
the input shaft is subjected to torsional vibration. The frequency of the torsional vibration on the input shaft changes according to the rigidity of the portion between the rotating electrical machine (12) and the input gear
Implementation Method 2
Depending on the frequency of the torsional vibration, the sound pressure and vibration that are generated may increase and may be transmitted to the case, increasing noise in the audible range
Data Source
AI summary
A vehicle drive device includes a rotating electrical machine, an input shaft including a first gear and connected to a rotor shaft, a counter gear mechanism, a differential gear mechanism, a pair of output members, and a case. The input shaft includes: a first supported portion supported by the case via a first bearing located on a first side in an axial direction with respect to the first gear; a connection portion located on the first side in the axial direction with respect to the first supported portion and connected to the rotor shaft; and a small diameter portion located between the first supported portion and the connection portion and having a diameter smaller than an outside diameter of the first supported portion and an outside diameter of the connection portion.