Multi-ratio Transmission with Nested Planetary Gearsets
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Solution Overview
Problem
Existing multi-step planetary transmissions for vehicles are complex, large, and heavy, with high drag and gearing losses, and require multiple shift elements for sequential shifting, which increases wear and installation space requirements.
Innovation Solution
A multi-step transmission design with four planetary gear sets and six shift elements, including brakes and clutches, optimized for reduced complexity, size, and weight, featuring a sequence of minus planetary gear sets to achieve nine forward gears and one reverse gear with minimal support moments, allowing for efficient gear ratios and reduced fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple shift elements are used to achieve sequential shifting in planetary transmissions, then gear ratio variability is improved, but device complexity and wear increase
Solution Approach 1:
The patent combines multiple shifting functions into a single shift element by using a common carrier that can selectively engage with different planetary gear sets. This single element performs the work of multiple traditional shift elements, reducing complexity while maintaining the ability to achieve various gear ratios through sequential engagement with different planetary stages.
Solution Approach 2:
The common carrier is designed as a universal shifting component that can interact with multiple planetary gear sets (first, second, and third planetary gears) through a single engagement interface. This multi-functional design allows one shift element to control multiple gear ratio changes, eliminating the need for separate shift elements for each planetary stage.
2Adaptability or versatility
If conventional planetary transmissions are designed with multiple gear sets, then transmission ratio range is improved, but size and weight increase
Solution Approach 1:
The patent employs nested planetary gear sets where the second planetary gear is positioned within the first planetary gear, and the third planetary gear is positioned within the second. This nested configuration allows multiple gear sets to occupy overlapping spatial volumes, significantly reducing the overall transmission size and weight while maintaining the ability to achieve a wide transmission ratio range through selective engagement of different planetary stages.
3Adaptability or versatility
If traditional sequential shifting is performed with multiple shift elements, then gear ratio coverage is improved, but double shifting requirements increase wear
Solution Approach 1:
By merging multiple shifting functions into a single common carrier that engages with different planetary gear sets, the patent eliminates the need for double shifting operations. The single shift element sequentially engages with first, second, and third planetary gears to achieve different gear ratios, reducing the frequency of shift element engagement and thereby reducing wear while maintaining comprehensive gear ratio coverage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design results in improved driving smoothness, reduced fuel consumption, lower wear, and minimized installation space, while enabling adaptable power flow directions and spatial configurations, with reduced drag and gearing losses.
Implementation Method 1
connected to a start-up element, such as a hydrodynamic torque converter or a fluid coupling, that is subject to a slip effect
Implementation Method 2
fluid coupling, that is subject to a slip effect and is provided optionally with a lock-up clutch
Data Source
AI summary
A multi step transmission comprising planetary gearsets (P1, P2, P3, P4), shafts and shift elements. The sun gear of gearset (P1) couples drive shaft (1). The carrier of set (P1) couples shaft (3), which couples housing (G) via brake (03), shaft (1) via clutch (13) and shaft (6) via clutch (36). Shaft (6) couples the ring and sun gear of gearsets (P2 P3) respectively, and, via clutch (68), shaft (8), which couples the carrier of gearset (P4). Shaft (1) couples the carrier of gearset (P4). Shaft (7) couples the ring gear of gearset (P1) and the carrier of set (P2). The sun gear of gearset (P4) couples shaft (4), which couples housing (G) via brake (04). The ring gear of gearset (P3) couples shaft (5), which couples housing (G) via brake (05). Output shaft (2) couples the carrier of gearset (P3) and the ring gear of gearset (P4).