Ring Gear Cup Vibration Decoupling in EV Drive
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Solution Overview
Problem
Existing drive devices for electric vehicles face challenges in optimizing acoustic properties, particularly in the meshing of ring gears, which can lead to undesirable noise and vibration.
Innovation Solution
A drive device with an electrical machine connected to a transmission device featuring a ring gear cup that is fixed to the housing via fasteners, allowing for radial intermeshing between the ring gear and the ring gear cup, providing vibration decoupling and acoustic optimization through a spur gear differential and planetary stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ring gear is directly fixed to the housing, then the structural simplicity is improved, but the acoustic properties deteriorate due to increased noise and vibration
Solution Approach 1:
The patent introduces a ring gear cup as an intermediary element between the ring gear and the housing. This cup acts as a mediator that decouples the direct connection, thereby reducing the transmission of vibrations and noise to the housing while maintaining structural integrity. The ring gear cup has internal teeth that mesh with the ring gear's external teeth, providing both mechanical support and vibration isolation.
2Object-generated harmful factors
If the ring gear cup is used for vibration decoupling, then the acoustic properties are improved, but the device complexity increases
Solution Approach 1:
The ring gear cup serves multiple functions simultaneously: it provides structural support for the ring gear, enables vibration decoupling through its flexible mounting to the housing, and contributes to the gear meshing mechanism through its internal teeth. This multi-functionality reduces the need for separate vibration isolation components, thereby limiting the increase in overall device complexity.
3Productivity
If the ring gear intermeshes radially between the second gear wheel and ring gear cup, then the transmission efficiency is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The radial intermeshing arrangement allows the ring gear to dynamically interact with both the second gear wheel and the ring gear cup. This dynamic configuration optimizes the transmission path and load distribution, improving transmission efficiency. The flexibility of the ring gear cup mounting also compensates for minor manufacturing tolerances, reducing the stringency of precision requirements.
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 effectively reduces noise and vibration by decoupling vibrations between the ring gear and the housing, enhancing the acoustic properties of the drive device and improving the overall operational quietness of the electric vehicle.
Implementation Method 1
The coupling between ring gear and housing by means of the ring gear cup serves in particular for vibration decoupling and thus for acoustic optimization of the meshing gears at the ring gear
Data Source
AI summary
A drive device for a motor vehicle includes an electrical machine which is operatively connected to a transmission device via a drive shaft. The transmission device has at least a first and a second planetary stage and a differential stage. Each planetary stage includes a planet set having a plurality of planet gears, the planet gears being rotatably arranged on a planet carrier and meshing with a sun gear and with a ring gear. The second ring gear has external teeth which mesh with internal teeth of a ring gear cup fixed to a housing in a stationary manner.