Hybrid Transaxle Layout for Compact Power Distribution
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Solution Overview
Problem
In hybrid transaxles, the compact space available for components is restricted by the engine compartment, making it challenging to optimize the arrangement of a planetary gearset, differential, generator, and traction motor while ensuring efficient power distribution and minimizing the risk of occupant injury in accidents.
Innovation Solution
A hybrid transaxle configuration that includes a planetary gearset, differential, countershaft, generator, and traction motor, where the traction motor is positioned forward of the engine axis, and the generator is positioned below, allowing for a compact design that reduces the risk of injury and optimizes power flow paths through multiple gear connections and planes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the transaxle components are arranged in a conventional layout, then the power flow paths are straightforward, but the transaxle length becomes too long and occupies excessive space in the engine compartment
Solution Approach 1:
The patent applies dimensional reconfiguration by arranging components along multiple axes rather than a single linear layout. The planetary gearset is positioned with its axis offset from the axle axis, the differential is placed below and behind the planetary gearset, the generator is located behind the planetary gearset, and the traction motor is positioned in front of the planetary gearset. This three-dimensional arrangement reduces the axial length of the transaxle while accommodating all necessary components within a compact volume.
Solution Approach 2:
The patent implements nested arrangement where the oil pan is positioned below the differential and countershaft, effectively utilizing the space underneath these components. The generator and traction motor are arranged on opposite sides of the planetary gearset axis, nesting their positions within the available radial space rather than extending the axial length. This nesting approach maximizes space utilization and reduces overall transaxle volume.
2Object-affected harmful factors
If the traction motor is positioned behind the planetary gearset, then the power flow is simplified, but the risk of occupant injury in front collisions increases
Solution Approach 1:
The patent introduces the planetary gearset as an intermediary component between the traction motor and the differential. The traction motor connects to the planetary gearset, which then connects to the differential through the countershaft. This intermediary arrangement positions the traction motor in front of the planetary gearset (reducing collision risk to occupants) while maintaining functional power flow through the gearset's mechanical connections, thus resolving the safety-complexity trade-off.
3Use of energy by moving object
If the generator and traction motor are positioned on the same side of the planetary gearset, then space is saved, but power distribution efficiency decreases
Solution Approach 1:
The patent employs asymmetric arrangement by positioning the generator and traction motor on opposite sides of the planetary gearset axis. The generator is located behind the planetary gearset while the traction motor is positioned in front of it. This asymmetric configuration optimizes the power flow paths for both energy conversion devices, allowing independent and efficient power distribution to the differential through the countershaft, while the overall layout remains compact due to the shared central position of the planetary gearset.
Data Source
AI summary
A hybrid transaxle permits location of a traction motor in a more favorable location, decreasing the risk of occupant injury in a vehicle collision. Axis transfer gearing moves the generator off the engine axis, which permits placing the traction motor further forward without interference with the generator. The gearing is confined to two gear planes, reducing the transaxle width.