Nested Friction Clutch Arrangement for Automatic Transmission
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Solution Overview
Problem
Automatic transmissions with dog clutches require rotational synchronization, leading to time delays during shifting, especially when transitioning between gears like Reverse (R) to Drive (D) or downshifting multiple gears.
Innovation Solution
A multi-speed automatic transmission design incorporating a friction disc clutch nested within another friction clutch hub, eliminating the need for rotational synchronization and enabling immediate engagement, thereby reducing shifting time delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dog clutch is used for gear shifting, then the transmission can achieve reliable gear engagement, but rotational synchronization is required which increases shifting time
Solution Approach 1:
The patent employs nested friction clutches where a first friction clutch is disposed within a second friction clutch, both sharing the same input shaft. This nested arrangement allows multiple clutches to be engaged simultaneously without requiring rotational synchronization, enabling immediate gear shifts while maintaining reliable engagement through the friction-based coupling mechanism.
2Manufacturing precision
If rotational synchronization is required for clutch engagement, then proper gear meshing is ensured, but the shifting duration is extended
Solution Approach 1:
The patent replaces the dog clutch mechanical engagement system with a friction clutch system. Friction clutches engage through frictional contact between clutch plates rather than mechanical interlocking of teeth, eliminating the need for rotational synchronization while ensuring proper power transmission through friction-based coupling.
3Speed
If multiple friction clutches are used to eliminate synchronization requirements, then shifting speed is improved, but the device complexity increases
Solution Approach 1:
The patent reduces system complexity by nesting friction clutches within the same radial space, allowing multiple clutches to share common components such as the input shaft and housing. This nested configuration achieves fast shifting without synchronization while minimizing the overall structural complexity compared to using separate dog clutches for each gear.
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 friction disc clutch arrangement provides smoother and more immediate gear shifts, eliminating synchronization requirements and associated delays, while maintaining compact packaging without extending the transmission length.
Implementation Method 1
a first friction clutch coupled the input shaft and having a hub, and a second friction clutch having a second hub and disposed about the input shaft
Data Source
AI summary
A multi-speed automatic transmission includes a housing, a transmission input shaft, and a plurality of clutches. Different combinations of clutches of the plurality of clutches are engaged to generate different gear ratios corresponding to respective forward speeds of the automatic transmission. The plurality of clutches are positioned within the housing and include a first friction clutch coupled the input shaft and having a first hub, and a second friction clutch having a second clutch hub. The second friction clutch is disposed about the input shaft and radially nested within the first clutch hub such that the second friction clutch is positioned radially between the first clutch hub and the input shaft. The first friction clutch is engaged to generate at least two forward speeds of the transmission and the second friction clutch is engaged to generate seven forward speeds of the transmission including the two forward speeds.