Nested Clutch Continuously Variable Transmission Design
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Solution Overview
Problem
Existing parallel path variator transmission systems are large and complex, consuming significant space and resources due to their design, which includes multiple countershafts and peripheral components, making them costly and inefficient.
Innovation Solution
A compact and efficient transmission system is achieved by using a nested clutch assembly and two coaxial planetary gear groups, allowing for two-speed ranges in both forward and reverse directions, eliminating the need for multiple countershafts and simplifying the design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a typical PPV system incorporates numerous countershafts and peripheral components, then the transmission provides excellent operational characteristics, but the system becomes large and complex with increased cost and footprint
Solution Approach 1:
The patent combines multiple planetary gear sets into integrated groups where gear sets share common components. The first planetary gear group contains a first planetary gear set and a second planetary gear set that share a common sun gear and carrier, reducing the number of independent components. Similarly, the second planetary gear group combines a third and fourth planetary gear set with shared components, eliminating the need for separate countershafts and reducing overall system complexity while maintaining operational characteristics
Solution Approach 2:
The patent implements a nested clutch assembly where a first selectable clutch and a second selectable clutch are arranged concentrically with one clutch nested within the other. This nested configuration allows both clutches to be integrated in a compact space without requiring separate mounting locations, reducing the peripheral space needed and simplifying the overall transmission layout while maintaining the ability to provide multiple speed ranges
2Reliability
If a typical PPV system incorporates numerous countershafts and peripheral components, then the transmission provides excellent operational characteristics, but the system footprint increases
Solution Approach 1:
The patent merges multiple planetary gear sets into two compact groups with shared components, eliminating the need for numerous separate countershafts and peripheral elements. This consolidation reduces the spatial footprint of the transmission system while preserving the operational characteristics provided by the multiple gear sets
Solution Approach 2:
The nested clutch assembly with concentric arrangement of clutches minimizes the peripheral space required for clutch mounting and operation, directly reducing the system footprint while maintaining the ability to provide multiple speed ranges for operational flexibility
3Reliability
If a typical PPV system incorporates numerous countershafts and peripheral components, then the transmission provides excellent operational characteristics, but the cost increases
Solution Approach 1:
The patent consolidates multiple planetary gear sets into integrated groups with shared components, reducing the total number of parts that need to be manufactured, assembled, and maintained. This merging approach lowers manufacturing costs while preserving the operational characteristics that require multiple gear sets
4Adaptability or versatility
If the nested clutch assembly uses first and second selectable clutches to fix the transmission in different speed ranges, then the transmission provides multi-range output, but the clutch assembly complexity increases
Solution Approach 1:
The patent arranges the first selectable clutch and second selectable clutch in a nested, concentric configuration where one clutch is positioned within the other. This nested arrangement integrates both clutches into a compact assembly, reducing the overall complexity compared to separate clutch installations while maintaining the ability to select between different speed ranges through independent clutch actuation
Data Source
AI summary
The described system and method provide a continuously variable full range transmission having inputs for receiving rotational power from a primary power source and a secondary power source such as a hydraulic variator. A first planetary gear group contains first and second planetary gear sets, and the inputs for receiving rotational power are linked to one or more of the first planetary gear set and the second planetary gear set. A second planetary gear group includes a third planetary gear set and a fourth planetary gear set, with a nested clutch assembly having first and second selectable clutches being provided to link the first planetary gear group to the second planetary gear group. Activation of the first clutch fixes the continuously variable transmission in a first speed range, while activation of the second clutch fixes the continuously variable transmission in a second speed range.