Electric Drive Unit Gear Layout for High Reduction in Compact Space
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Solution Overview
Problem
Existing electric drive modules face challenges in achieving a compact design while providing a high overall reduction ratio.
Innovation Solution
The electric drive unit incorporates an electric motor, input pinion, multiple reduction gears, and a differential assembly, with specific bearing configurations and a planetary reduction mechanism to achieve a compact and efficient power transmission system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high overall reduction ratio is achieved through conventional transmission design, then the reduction capability is improved, but the transmission size and complexity increase
Solution Approach 1:
The patent employs a planetary gear set where planet gears are nested around a sun gear, with ring gears enclosing the entire planetary assembly. This nested configuration allows multiple gear stages to occupy a compact radial space, achieving high reduction ratios without proportionally increasing transmission volume. The planet gears rotate on their own axes while simultaneously orbiting the sun gear, creating a compact multi-stage reduction mechanism.
Solution Approach 2:
The transmission design utilizes three-dimensional spatial arrangement by positioning the planetary gear set concentrically around the motor output shaft. The sun gear is coaxial with the motor shaft, planet gears extend radially outward, and ring gears provide outer containment. This dimensional arrangement allows power transmission through multiple gear stages while maintaining a compact footprint by utilizing radial and axial space efficiently.
2Power
If multiple reduction gears are added to increase the reduction ratio, then the power transmission capability is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple gear reduction functions into a single integrated planetary gear set. The sun gear, planet gears, and ring gear work together as one unified mechanism to achieve the overall reduction ratio, eliminating the need for separate sequential gear stages. This merging of multiple reduction functions into a single compact unit reduces the number of independent components and simplifies the overall transmission architecture.
Solution Approach 2:
The planetary gear set serves multiple functions simultaneously: it provides the primary reduction ratio, transmits power from the motor to the differential, and enables compact packaging of the transmission system. The same gear components that provide reduction also serve as structural elements that define the transmission housing space and support bearing locations, reducing the need for additional dedicated components.
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 enables a compact transmission design with a high reduction ratio, enhancing power transmission efficiency and flexibility.
Implementation Method 1
The input pinion is driven by the motor output shaft about the first rotational axis. Each of the first reduction gears is meshingly engaged with the input pinion and is rotatable about a respective second rotational axis that is parallel to the first rotational axis.
Data Source
AI summary
An electric drive unit with an electric motor, an input pinion, which is driven by an output shaft of the electric motor about a first axis, a pair of first gears, each of which is meshed with the input pinion and rotatable about a respective second axis, a second gear, which is meshed with the first gears and rotatable about a third axis, a third gear, which is driven by the second gear about the third axis, a fourth gear, which is meshed with the third gear and rotatable about a fourth axis, and a differential having a differential input, which is rotatably coupled to the third gear, and a pair of differential outputs that are driven by the differential input and rotatable about the fourth axis. The first, second, third and fourth axes are parallel to one another. The third axis is offset from the first and second axes.