Planetary Automatic Transmission With Five Gearsets
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Solution Overview
Problem
Existing automatic transmissions in planetary design with seven shift elements face challenges in achieving a wide range of gear ratios while minimizing construction costs and avoiding group shifting, which complicates sequential shifting.
Innovation Solution
An automatic transmission design featuring five planetary gearsets and seven shift elements, allowing for up to fourteen forward gears and two reverse gears without group shifting, by configuring each planetary gearset as either a minus or plus gearset and strategically connecting shift elements to achieve independent kinematics and efficient gear progression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of planetary gearsets is increased to achieve more gear ratios, then the gear ratio range is improved, but the device complexity increases
Solution Approach 1:
The patent combines five planetary gearsets into a single integrated transmission system where multiple gearsets share common components (sun gears, ring gears, planetary carriers) and are controlled by a unified set of seven shift elements. This merging approach achieves a wide gear ratio range (14 forward gears + 2 reverse gears) while limiting complexity growth through component sharing and centralized control.
2Ease of manufacture
If the number of shift elements is reduced to lower construction costs, then the manufacturing cost is improved, but the number of achievable gear ratios is limited
Solution Approach 1:
Each of the seven shift elements is designed to perform multiple functions by selectively engaging different planetary gearsets and controlling multiple gear ratios. For example, a single shift element can control torque flow through different gearsets depending on the selected gear, allowing the system to achieve 14 forward gears and 2 reverse gears with only seven shift elements instead of requiring one shift element per gear ratio.
Solution Approach 2:
The transmission system is segmented into five distinct planetary gearsets (first through fifth), each capable of independent torque transmission. This segmentation allows the seven shift elements to selectively engage different gearsets for different gear ratios, enabling diverse gear options while maintaining cost efficiency through the use of a limited number of control elements.
3Ease of operation
If group shifting is avoided for simpler sequential shifting, then the ease of operation is improved, but the device complexity must be managed to enable smooth gear transitions
Solution Approach 1:
The patent employs a dynamic kinematic configuration where the torque flow path changes continuously based on the selected gear ratio. The system uses seven shift elements that can be selectively engaged or disengaged to create different torque transmission paths through the five planetary gearsets, enabling smooth sequential shifting without group shifting while adapting the kinematic structure to each gear position.
4Adaptability or versatility
If the number of planetary gearsets is increased to achieve more gear ratios, then the gear ratio range is improved, but the manufacturing cost increases
Solution Approach 1:
The patent merges five planetary gearsets into a compact integrated system where components are shared across multiple gearsets. The seven shift elements control torque flow through this merged structure, achieving a wide gear ratio range (14 forward + 2 reverse gears) while limiting manufacturing cost increases through component consolidation and efficient space utilization.
Solution Approach 2:
The seven shift elements are designed with universal functionality to control multiple planetary gearsets simultaneously or selectively. This multi-functionality reduces the total number of control components needed, thereby lowering manufacturing costs while still enabling the transmission to achieve a wide range of gear ratios through coordinated engagement of different gearsets.
Data Source
AI summary
A transmission having five planetary gearsets and seven shift elements for achieving various ratios between drive and output shafts. A forward gearset has three shafts. Two intermediate gearsets have four shafts. Two main gearsets have at least four shafts. Depending on the shift states of the second and third shift elements, the forward gearset can generate two rotational speeds at the output side, which transfer from a forward gearset shaft to an intermediate gearset shaft. Depending on the shift states of the first to fifth shift elements, the intermediate gearset can generate eight rotational speeds at the output side, which pass from another intermediate gearset shaft to a main gearset shaft. Depending on the shift states of the seven shift elements, the main gearset can generate up to fourteen forward and two reverse gears at the output side, which are transferred by another main gearset shaft to the output shaft.