Planetary Drive Unit Noise Reduction via Helical Gears and Sintered Ring
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Solution Overview
Problem
Drive units, particularly those with gear reduction systems, emit significant noise during high-speed operations, which is considered noise pollution, and are too loud in applications requiring quiet operation, such as in electric mowers and powered lift gates.
Innovation Solution
A drive unit comprising a motor with a planetary gear train featuring helical sun and planetary gears, a ring gear made by sintered powder metallurgy, and quick aligning structures for assembly, which reduces noise through increased meshing surfaces and uses plastic planetary gears for further noise reduction, while being cost-effective and manufacturable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a planetary gear train is used for gear reduction, then the transmission efficiency is improved, but the noise level increases
Solution Approach 1:
The ring gear is manufactured using sintered powder metallurgy, creating a composite structure with porous characteristics that effectively dampens noise while maintaining the gear reduction function. This composite material approach allows the gear train to maintain transmission efficiency while significantly reducing the noise generated during operation.
Solution Approach 2:
The invention changes the physical and chemical parameters of the ring gear material through sintering processes, creating a material with specific porosity and damping characteristics. This parameter change enables the ring gear to absorb and dissipate vibration energy, thereby reducing noise while preserving the mechanical transmission efficiency of the planetary gear train.
2Ease of manufacture
If traditional manufacturing methods are used for the ring gear, then the manufacturing cost is reduced, but the noise reduction effect is insufficient
Solution Approach 1:
The sintered powder metallurgy process changes the material parameters of the ring gear, creating a porous structure with noise-damping properties. This parameter change is achieved through controlled sintering that creates interconnected voids capable of absorbing vibration energy, thereby reducing noise while maintaining cost-effectiveness.
Solution Approach 2:
The ring gear is manufactured as a porous material using sintered powder metallurgy. The porous structure provides numerous interfaces for vibration energy dissipation and acoustic wave absorption, significantly reducing noise generation while maintaining the structural integrity and load-bearing capacity required for cost-effective manufacturing.
3Stability of the object's composition
If helical gears are used in the planetary gear train, then the operational stability is improved, but the manufacturing complexity increases
Solution Approach 1:
The invention merges the helical gear cutting process with the sintering process by cutting the helical teeth into the green compacted ring gear before sintering. This combination eliminates the need for separate post-sintering machining operations, reducing manufacturing complexity while maintaining the operational stability benefits of helical gear engagement.
Solution Approach 2:
The helical gear teeth are cut into the ring gear while it is in the green compacted state, before the sintering process. This preliminary action allows the complex helical geometry to be established early in the manufacturing process when the material is more formable, simplifying subsequent sintering and finishing operations while ensuring precise helical tooth geometry for stable operation.
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 drive unit achieves stable operation with significantly reduced noise levels, making it suitable for applications requiring quiet operation, such as electric mowers and powered lift gates, while maintaining cost-effectiveness and manufacturability.
Implementation Method 1
the first ring gear is made by sintered powder metallurgy
Data Source
AI summary
The planetary gear train includes a first sun gear driven by the motor, a first ring gear, a first carrier, and a plurality of first planetary gears arranged at one side of the first carrier and meshing with the first sun gear and the first ring gear. The first sun gear, first planetary gears and first ring gear are helical gears so that meshing surface is increased. Helical teeth formed on an inner surface of the first ring gear mesh with the helical teeth of the first planetary gears. Therefore, the operation is stable and the noise is low. The planetary gears are made of plastic to further decrease the noise. The first ring gear is made by sintered powder metallurgy.