Planetary-Belt Gear Assembly for High Ratio, Low-Noise EV Drives
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Solution Overview
Problem
Conventional multi-stage gear arrangements for power transmission in vehicles, particularly in electric vehicles, face challenges of high weight, large installation space, significant unsprung mass, noise emissions, and maintenance issues due to the need for multiple gear stages and lubrication systems, especially when achieving high gear ratios.
Innovation Solution
A multi-stage gear arrangement combining an epicyclic gear and a tension belt drive within a common gear housing, allowing for a high overall gear ratio with reduced weight, compact design, low maintenance, and minimized lubrication needs, featuring a series connection of planetary gears and a tension belt drive to achieve high torque transmission with reduced noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional multi-stage gear arrangements are used to achieve high gear ratios, then the required transmission ratio is achieved, but the weight of the transmission increases significantly
Solution Approach 1:
The transmission is divided into multiple independent stages, each providing a portion of the total gear ratio. This allows the use of lighter individual gear stages rather than one heavy high-ratio stage, distributing the weight burden while achieving the cumulative high gear ratio needed for electric vehicle applications
Solution Approach 2:
The invention changes the physical parameters of the transmission system by using different gear stage configurations (planetary vs. parallel shaft), varying tooth counts, and optimizing center distances to reduce overall weight while maintaining the required high gear ratio performance
2Power
If multiple gear stages are used to achieve high gear ratios, then the transmission ratio is achieved, but the installation space and center distances increase
Solution Approach 1:
Planetary gear stages are nested within the transmission housing in a compact arrangement where the planetary gears are contained within the annulus, allowing multiple gear stages to be stacked or arranged in a space-efficient manner that minimizes the overall footprint and center distances between stages
3Reliability
If oil lubrication is provided through separate pumps and circulation channels, then sufficient lubrication is achieved, but the device complexity and maintenance requirements increase
Solution Approach 1:
The complex oil pump and circulation channel system is extracted and replaced with a simpler lubrication approach. The invention uses direct oil delivery to critical gear meshing points, eliminating the need for separate pumps and extensive circulation channels while maintaining sufficient lubrication for reliable operation
Solution Approach 2:
The transmission design incorporates features that enable self-lubrication or simplified lubrication, such as gravity-assisted oil flow to gear meshes or integrated lubrication paths within the gear structure itself, reducing or eliminating the need for external lubrication systems
4Power
If high gear ratios with multiple meshing gears are used, then the required transmission ratio is achieved, but noise emissions increase considerably
Solution Approach 1:
The invention incorporates vibration damping elements and noise reduction features into the gear design before the noise is generated. This includes using damped gear tooth profiles, vibration isolation mounts, and acoustic insulation within the transmission housing to cushion and absorb noise and vibration from the meshing gears before they propagate outward
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 provides a lightweight, compact, low-maintenance transmission with reduced noise and vibration, capable of achieving high gear ratios without excessive weight increase, suitable for high-speed electric motors, and allows for flexible installation and adaptation in various vehicle applications.
Implementation Method 1
a tension belt drive (32, 43) is provided... which wraps around the ring gear (31)... and a driven pulley (33, 44)... for the transmission of a torque and a speed
Implementation Method 2
a tension belt drive (32, 43)... in which the belt (32, 43) wraps around the externally toothed sun wheel and the externally toothed planetary wheels
Implementation Method 3
at least two gear stages (28-31, 34-38) designed as planetary gears... first planetary gears (29)... first sun gear (30)... ring gear (31)... second planetary gears (37, 38)... second sun gears (35, 36)... second ring gear (39)
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a multistage gear assembly for transmitting power between shafts, wherein at least one gear stage in the form of planetary gear train and a gear stage in the form of a traction belt drive are arranged in the force or power flow within a common gear housing and preferably each have a fixed, non-shiftable gear ratio.