Off-Axis Motor Generators for Hybrid Transmission Packaging
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Solution Overview
Problem
Conventional electrically variable transmissions with on-axis motor/generators face packaging design limitations, particularly in front wheel drive applications due to limited space along the transmission input axis.
Innovation Solution
The electrically variable transmission incorporates a first motor/generator rotating about a third axis and a second motor/generator rotating about the transmission input axis, allowing for improved packaging flexibility by reducing the space required along the transmission input axis, with optional configurations where both motor/generators share a common off-axis or separate axes distinct from the input axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If motor/generators are located on the transmission input axis, then the transmission structure is simplified, but the packaging design flexibility is significantly limited
Solution Approach 1:
The patent moves at least one motor/generator from the traditional on-axis configuration to an off-axis configuration, utilizing the third dimension (radial direction) for motor placement. This dimensional change allows motors to be positioned in previously unavailable space around the input shaft, thereby improving packaging flexibility without significantly complicating the transmission structure.
2Ease of manufacture
If two motor/generators are located on the transmission input axis, then the alignment is simplified, but the available space is significantly limited
Solution Approach 1:
By positioning at least one motor/generator off the transmission input axis, the patent utilizes radial space that would otherwise be unavailable. This allows both motors to be accommodated within the transmission housing without requiring extended axial length, thereby increasing the effective available space while maintaining reasonable alignment through appropriate mounting structures.
3Adaptability or versatility
If motor/generators are positioned for optimal packaging, then space utilization is improved, but the structural complexity increases
Solution Approach 1:
The off-axis motor configuration utilizes radial space around the input shaft, allowing optimal packaging without requiring complex structural modifications. The motor can be mounted on the housing or support structures that already exist in the radial direction, minimizing additional structural complexity while maximizing packaging flexibility.
Solution Approach 2:
The patent designs the transmission housing and support structures to serve multiple functions: providing structural support, accommodating off-axis motor mounting, and facilitating heat dissipation. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in structural complexity while achieving optimal packaging.
Data Source
AI summary
The present invention provides an electrically variable transmission for a hybrid vehicle. The electrically variable transmission includes a transmission input shaft defining a first axis of rotation, and a transmission output shaft defining a second axis of rotation. A first motor/generator is operatively connected to the transmission input shaft and is configured to rotate about a third axis of rotation for improved packaging. A second motor/generator is operatively connected to the transmission input shaft and is configured to rotate about the first axis of rotation.