Ravigneaux Gearset Two-Mode Electric Drive Module
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Solution Overview
Problem
Existing electric drive modules with large internal gears are costly to manufacture and require an improved design for efficiency and cost-effectiveness.
Innovation Solution
A two-mode electric drive module incorporating a Ravigneaux gearset with a carrier, sun gears, planet gears, differential assembly, and shift member, which allows for torque transmission and adjustment between different operational modes, including propulsion, torque boost, and torque vectoring, using two electric motors and a reduction gearset to optimize gear engagement and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large internal gears are used in the transmission, then torque transmission capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs a Ravigneaux gearset where a second set of planet gears (with larger pitch diameter) is nested within the first set of planet gears (with smaller pitch diameter). Both sets share a common carrier and rotate about the same sun gear, allowing the larger gear elements to be contained within the existing transmission structure rather than requiring separate large external gears, thus reducing manufacturing complexity and cost while maintaining torque transmission capability
Solution Approach 2:
The patent transitions from a conventional single-stage planetary gear arrangement to a two-stage Ravigneaux configuration by adding the dimensional complexity of nested planet gear sets. This allows torque multiplication to be achieved through the interaction of two different planet gear pitch diameters (first and second values) rather than requiring a single large gear, effectively using structural dimensionality to reduce manufacturing costs while preserving power transmission
2Adaptability or versatility
If a two-stage planetary transmission with large internal gears is used, then gear ratio range is improved, but device complexity increases
Solution Approach 1:
The patent merges two planetary gear stages into a single compact Ravigneaux assembly where the first and second planet gears share a common carrier, sun gear, and housing. This consolidation achieves multiple gear ratios through the interaction of the two planet gear sets without requiring separate transmission stages, thereby reducing overall structural complexity while maintaining an expanded gear ratio range
Solution Approach 2:
The Ravigneaux gearset structure serves multiple functions simultaneously: the common carrier supports both first and second planet gears, the sun gear interacts with both planet gear sets, and the housing provides mounting for all components. This multi-functionality allows the transmission to achieve varied gear ratios through a unified structure rather than requiring multiple specialized components, reducing device complexity while expanding adaptability
Data Source
AI summary
A drive module includes a Ravigneaux gearset, first and second input shafts, shift member, and differential. The first planet gears of the gearset can engage the first sun gear and the second planet gears, which can engage the second sun gear. The first input shaft can rotate with the second sun gear and receives torque from a first motor. A first gear can be coupled to the carrier of the Ravigneaux gearset for rotation therewith and meshingly engages the differential input. The second input shaft receives torque from a second motor and is drivingly coupled to the differential input. When the shift member is in a first position, the shift member drivingly couples the first sun gear to a first differential output. When the shift member is in a second position, the shift member couples the first sun gear to a housing to prevent rotation of the first sun gear.