Planetary Transmission Coupler Layout for Nine Forward and Reverse Speeds
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Solution Overview
Problem
Existing multi-speed transmissions face challenges in achieving a large number of forward and reverse speed ratios efficiently, as they often require complex configurations of planetary gearsets and selective couplers, which can lead to increased complexity and cost.
Innovation Solution
A multi-speed transmission design incorporating five planetary gearsets and eight selective couplers, including clutches and brakes, to achieve at least nine forward and nine reverse speed ratios by selectively engaging these couplers in various combinations, allowing for efficient torque transfer and direction reversal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of forward and reverse speed ratios are achieved using conventional planetary gearsets and selective couplers, then the transmission provides comprehensive speed control, but the device complexity increases significantly
Solution Approach 1:
The transmission system is divided into multiple independent planetary gearsets (first, second, third, fourth, and fifth planetary gearsets), each capable of providing specific speed ratios. By segmenting the overall transmission function into separate gearsets, the system achieves multiple speed ratios while maintaining manageable complexity in each individual gearset.
Solution Approach 2:
The selective couplers (clutches and brakes) are designed to serve multiple functions across different planetary gearsets. The same type of coupler can engage different components in various gearsets to achieve both forward and reverse speed ratios, reducing the need for dedicated couplers for each function and thereby simplifying the overall system.
2Adaptability or versatility
If five planetary gearsets and eight selective couplers are used to achieve nine forward and nine reverse speed ratios, then the transmission provides wide speed range control, but the manufacturing cost increases
Solution Approach 1:
Multiple planetary gearsets are merged into a single integrated transmission system with shared components and common housing. The gearsets are arranged concentrically around a common axis, allowing them to share manufacturing processes, materials, and assembly procedures, thereby reducing overall manufacturing costs despite the increased number of gearsets.
Solution Approach 2:
The system uses standard planetary gearset configurations with varying tooth counts and gear ratios to achieve different speed ratios. By changing the parameters (number of teeth, gear dimensions) of existing gearsets rather than designing completely different mechanisms for each ratio, the manufacturing process is simplified and costs are reduced.
3Productivity
If multiple selective couplers are engaged to establish forward and reverse speed ratios, then the transmission achieves efficient torque transfer, but the control complexity increases
Solution Approach 1:
The selective couplers are designed to be dynamically engaged and disengaged based on the desired speed ratio and direction. The control system actively manages which couplers are engaged at any given time, allowing the transmission to adapt to different operating conditions and maintain efficient torque transfer while managing control complexity through systematic engagement patterns.
Data Source
AI summary
A multi-speed transmission including a plurality of planetary gearsets and a plurality of selective couplers to achieve at least nine forward speed ratios and at least nine reverse speed ratios is disclosed. The plurality of planetary gearsets may include a first planetary gearset, a second planetary gearset, a third planetary gearset, a fourth planetary gearset, and a fifth planetary gearset. The plurality of selective couplers may include a number of clutches and a number of brakes. The multi-speed transmission may have five planetary gearsets and eight selective couplers. The eight selective couplers may include three clutches and five brakes.