Planetary Ring Gear Mount With Plastic Damping Interface
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Solution Overview
Problem
Existing electric drive devices for motor vehicles suffer from excessive noise due to direct contact between metal toothings in the planetary gear set, leading to undesirable noise transmission.
Innovation Solution
Incorporating a plastics ring between the internal and external toothings of the transmission housing and ring gear to prevent direct contact, using a plastics ring injection-molded onto the internal toothing to ensure surface contact and damping of vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If metal toothings are used in direct contact for torque transmission, then torque transmission efficiency is improved, but noise transmission increases excessively
Solution Approach 1:
A plastics ring is introduced as an intermediary element between the internal toothing of the transmission housing and the external toothing of the ring gear. This plastics ring serves as a mediator that transmits torque while simultaneously damping vibrations and reducing noise, preventing direct metal-to-metal contact that would otherwise transmit excitations undamped to the housing.
Solution Approach 2:
The solution employs a composite material approach by using a plastics ring instead of pure metal contact surfaces. The plastics material combines torque transmission capability with inherent damping properties, creating a composite interface that achieves both power transmission and noise reduction functions.
2Object-generated harmful factors
If a plastics ring is arranged between the toothings to reduce noise, then noise transmission is reduced, but torque transmission capability must be maintained
Solution Approach 1:
The plastics ring is designed with specific material parameters and geometric dimensions optimized for both torque transmission and vibration damping. By adjusting parameters such as material density, elasticity, ring thickness, and contact surface area, the design achieves adequate torque capacity while maintaining effective noise reduction through controlled deformation and energy dissipation.
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 approach significantly reduces noise transmission by decoupling excitation from the ring gear to the housing, achieving improved noise, vibration, and harshness (NVH) behavior.
Implementation Method 1
Depending on the layer thickness and type of plastics material, excitations of the ring gear, formed as an internal component, can be decoupled so that excessive noise can be avoided. In other words, noise damping can be achieved with the plastics ring
Data Source
AI summary
An electric drive device for a motor vehicle includes an electric motor for driving the motor vehicle and a planetary gear set which has a ring gear and is disposed in a transmission housing formed from a die-cast material. The transmission housing has a moulded internal toothing as the first toothing into which a corresponding external toothing disposed on the ring gear engages as the second toothing such that the ring gear is connected to the transmission housing for conjoint rotation. There is disposed between the toothings a plastics ring via which the toothings are supported against each other.