Infinitely Variable Transmission Gear Scheme with Planetary Variator
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Solution Overview
Problem
Existing continuously variable transmissions (CVTs) for powered vehicles often require complex architectures and multiple clutches to achieve infinitely variable transmission modes, which can increase length and complexity, making them less efficient and more costly.
Innovation Solution
A gear scheme with a double shunt architecture and fewer than four output gearsets, utilizing a toroidal variator and strategically positioned planetary gearsets to provide multiple operating modes, including a geared neutral mode and multiple forward ranges, with clutches engaging and disengaging to switch between modes synchronously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If complex architectures with multiple clutches are used to achieve infinitely variable transmission modes, then multiple operating modes including geared neutral can be provided, but the transmission length and complexity increase
Solution Approach 1:
The patent combines the geared neutral function and multiple forward ratio ranges into a single integrated planetary gearset architecture. The sun gear, planet gears, and ring gear work together as one unified system where the carrier can be locked or unlocked to provide geared neutral, while the variator continuously varies the ratio within each range. This merging eliminates the need for separate clutch mechanisms for each mode, reducing overall complexity while maintaining versatility.
Solution Approach 2:
The planetary gearset is designed as a universal mechanism that performs multiple functions: it provides geared neutral operation, enables continuous ratio variation through the variator, and delivers multiple forward ratio ranges. The single planetary assembly replaces what would traditionally require multiple separate gearsets and clutch mechanisms, achieving multi-functionality with reduced complexity.
2Adaptability or versatility
If multiple clutches are used to switch between operating modes, then mode switching capability is improved, but the transmission length increases
Solution Approach 1:
The patent merges the mode switching function into a single clutch mechanism that controls the carrier engagement with the ring gear. This single clutch replaces what would traditionally require multiple separate clutch mechanisms, significantly reducing the axial length of the transmission while maintaining the ability to switch between geared neutral and forward ratio ranges.
Solution Approach 2:
The patent arranges the planetary gearset components (sun gear, planet gears, ring gear, carrier) in a compact radial and axial configuration that minimizes transmission length. The variator is positioned to work integrally with the planetary assembly, allowing ratio variation without requiring additional axial space for separate mechanism stacks.
3Adaptability or versatility
If complex gear schemes are used to provide multiple forward ranges, then operating mode versatility is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines multiple forward ratio ranges into a single planetary gearset system that works continuously with the variator. Instead of manufacturing and assembling multiple separate gearsets for different ranges, the invention uses one integrated planetary assembly where the ratio range is determined by the variator's operation. This significantly simplifies manufacturing and assembly processes while maintaining the capability to provide multiple forward ranges.
Solution Approach 2:
The planetary gearset is designed as a universal mechanism that handles all forward ratio ranges through its continuous operation with the variator. The same sun gear, planet gears, and ring gear assembly provide all forward ranges, eliminating the need for multiple specialized gearsets and reducing manufacturing complexity.
Data Source
Figure 1A~1B
Figure 1C~3C
Figure 2A~2B
AI summary
A gear scheme for an infinitely variable transmission includes an input shaft, an output shaft, a variator, and a pair of planetary gearsets located beside the variator rather than in front of or behind the variator. The variator and the planetary gearsets are coupled between the input and output shafts.