Drive Axle Planetary Gear Layout for Symmetrical Torque Split
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Solution Overview
Problem
Existing motor vehicle drive axles face challenges in achieving symmetrical torque distribution and high transmission ratios while maintaining a compact design, particularly in electric axle drives.
Innovation Solution
The axle gear system incorporates a planetary stage with a fixed carrier train ratio of less than negative one (-1) and coordinated intermediate transmissions to achieve symmetrical torque distribution and high transmission ratios, utilizing a sun gear, ring gear, and planet carrier with planet gears, and optionally includes spur gear stages or flexible traction drive mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a planetary stage with fixed carrier train ratio less than negative one is used, then high transmission ratio is achieved, but radial space requirement increases
Solution Approach 1:
The patent applies asymmetry by using a fixed carrier train ratio that is less than negative one (asymmetric value) rather than a symmetric -1 ratio. This asymmetric ratio enables higher transmission ratio while the coordinated intermediate transmissions balance the asymmetric torque distribution to achieve symmetrical output, resolving the contradiction between high transmission ratio and compact radial design
Solution Approach 2:
The patent changes the carrier train ratio parameter to a specific asymmetric value less than negative one, and coordinates the intermediate transmission ratios to compensate. This parameter optimization allows achieving high transmission ratio in a radially compact configuration by mathematically balancing the torque distribution despite the asymmetric planetary stage
2Stability of the object's composition
If planetary stage with fixed carrier train ratio less than negative one is used, then symmetrical torque distribution is achieved, but device complexity increases
Solution Approach 1:
The patent intentionally introduces asymmetry in the planetary stage (fixed carrier train ratio less than negative one) and compensates it through coordinated intermediate transmissions. This controlled asymmetry approach achieves symmetrical torque distribution at the output while managing complexity through systematic ratio coordination rather than requiring symmetric planetary configurations
Solution Approach 2:
The patent introduces intermediate transmissions as intermediary components between the planetary stage and the final output. These intermediaries serve as mediators that transform the asymmetric torque distribution from the planetary stage into symmetrical output, adding controlled complexity to achieve the desired torque distribution symmetry
Data Source
AI summary
An axle gear system (8) includes a planetary stage (14), a first driven shaft (13) and a second driven shaft (11). The planetary stage (14) has a fixed carrier train ratio of less than negative one (−1). A sun gear (19) of the planetary stage (14) is connected to a drive shaft (9) for conjoint rotation. A planet carrier (20) is connected to a first output shaft (12) for conjoint rotation. The first output shaft (12) is coupled to the first driven shaft (13) via a first intermediate transmission (16). A ring gear (21) is connected to a second output shaft (10) for conjoint rotation. The second output shaft (10) is coupled to the second driven shaft (11) via a second intermediate transmission (15). Transmission ratios of the first and second intermediate transmissions (15, 16) are coordinated such that, in combination with the fixed carrier train ratio of the planetary stage (14), a symmetrical torque distribution from the drive shaft (9) onto the driven shafts (11, 13) is established.