Electrically-Variable Transmission Nested Motor-Gear Packaging
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Solution Overview
Problem
Electrically-variable transmissions face challenges in packaging motor/generators, planetary gear sets, and clutches while meeting dimensional limitations and assembly simplicity, and they are not widely adopted due to high engineering and tooling costs.
Innovation Solution
The design includes a casing with a cavity housing two planetary gear sets, two motor/generators, and torque-transmitting mechanisms, with the second planetary gear set positioned between the motor/generators and a damper mechanism coupled to the input member and first planetary gear set, optimizing packaging and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two motor/generators, planetary gear sets, and multiple clutches are packaged to achieve desired modes of operation, then functional versatility is improved, but device complexity and packaging difficulty increase
Solution Approach 1:
The patent implements nesting by placing the second planetary gear set between the first and second motor/generators along the rotational axis, with the first torque-transmitting mechanism disposed between the motor/generators. This nested arrangement allows multiple functional components to occupy overlapping radial and axial spaces, achieving compact packaging while maintaining all required operational modes including electrically-variable modes, fixed speed ratio modes, and electric-only mode.
Solution Approach 2:
The patent utilizes the radial dimension by arranging components in concentric configurations around the rotational axis. The planetary gear sets are positioned with sun gears, carriers, and ring gears occupying different radial zones, while the motor/generators are spaced along the axial dimension. This multi-dimensional spatial organization resolves packaging complexity by efficiently utilizing three-dimensional space within the transmission housing.
2Volume of moving object
If components are arranged to meet dimensional limitations, then compactness is improved, but assembly simplicity deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the transmission into distinct functional modules: first planetary gear set with its torque-transmitting mechanism, second planetary gear set positioned between the motor/generators, and damper mechanism coupled to the input member. Each module can be independently positioned and assembled along the rotational axis, simplifying the assembly process while achieving compact overall volume through the linear arrangement of these modular segments.
3Ease of manufacture
If engineering and tooling costs are reduced for mass production, then manufacturing cost is improved, but development investment decreases
Solution Approach 1:
The patent implements universality through the first torque-transmitting mechanism that is selectively actuated to ground the ring gear of the second planetary gear set, enabling multiple operational modes (electrically-variable modes, fixed speed ratio modes, and electric-only mode) with a single mechanism. This multi-functional design reduces the total number of specialized components required, thereby lowering engineering and tooling costs for mass production while maintaining versatile operational capabilities.
Data Source
AI summary
An electrically-variable transmission for a vehicle is disclosed. The transmission includes an input member and an output member each rotatable about a first axis. The transmission includes a casing defining a cavity between a first end wall and a second end wall. The transmission includes a first motor/generator and a second motor/generator disposed in the cavity with a second planetary gear set disposed between the first and second motor/generators along the first axis. The transmission includes a first torque-transmitting mechanism disposed between the first and second motor/generators along the first axis. The transmission includes a second torque-transmitting mechanism disposed between the first end wall and the first motor/generator along the first axis. The first motor/generator is disposed between the first and second torque-transmitting mechanisms along the first axis. The transmission includes a damper mechanism disposed between the second end wall and a first planetary gear set along the first axis.