Twin Countershaft CVT Synchronous Shifting for Continuous Ratios

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Solution Overview

Problem

Current power transmission systems, particularly automatic transmissions, lack efficient mechanisms for synchronous shifting, which limits their ability to dynamically adjust transmission ratios and optimize power distribution across multiple gear sets, leading to suboptimal performance and efficiency.

Innovation Solution

A drivetrain system incorporating a planetary gearset, variator, and a control system with multiple clutches and gears that allows for synchronous shifting by adjusting the speed ratio of the variator and engaging/disengaging clutches to change transmission ratios across different modes, enabling continuous and efficient power transmission through multiple power paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If synchronous shifting is implemented with multiple clutches and gear sets, then the transmission ratio adjustment capability and power distribution efficiency are improved, but the device complexity and control difficulty increase

Engineering Contradiction:

Improvetransmission ratio adjustment capabilityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The transmission system is divided into multiple independent gear sets (first gear set, second gear set) with separate clutches (first clutch, second clutch) that can be engaged or disengaged independently. This segmentation allows the system to achieve multiple transmission ratios by selectively activating different gear sets, thereby improving adaptability while managing complexity through modular design

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The planetary gearset serves multiple functions by working in conjunction with the variator and multiple clutches to provide both continuous variable transmission ratio adjustment and discrete gear shifting capabilities. The single planetary gearset structure is utilized across different modes (first mode, second mode) to achieve various transmission ratios, reducing the need for separate mechanisms

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Productivity

If synchronous shifting with twin countershafts is used, then the power distribution efficiency and transmission ratio range are improved, but the manufacturing complexity and cost increase

Engineering Contradiction:

Improvepower distribution efficiencyVSAvoidmanufacturing complexity

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The transmission system employs twin countershafts (first countershaft, second countershaft) that are segmented and can be independently controlled through respective clutches. This allows power to be distributed efficiently to different gear sets based on operational requirements, improving productivity while the modular segmented structure facilitates manufacturing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The planetary gearset is merged with the variator mechanism to create an integrated power transmission system that combines continuous variable transmission capability with discrete gear shifting. This merging reduces the total number of separate components needed, thereby reducing manufacturing complexity while maintaining high power distribution efficiency

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If the variator speed ratio is continuously adjusted, then the transmission ratio optimization and performance adaptability are improved, but the control system complexity and energy consumption increase

Engineering Contradiction:

Improveperformance adaptabilityVSAvoidenergy consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The control system operates the variator and clutches in periodic cycles, switching between first mode and second mode based on operational requirements. The clutches are engaged and disengaged periodically to shift between gear sets, and the variator speed ratio is adjusted periodically rather than continuously, reducing energy consumption while maintaining performance adaptability

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The planetary gearset maintains continuous engagement with the variator throughout operation, ensuring uninterrupted power transmission and continuous useful action. This continuous engagement allows for smooth transitions between modes and continuous optimization of transmission ratios without energy-wasting disengagements, improving energy efficiency while maintaining adaptability

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS12173778B2Continuously variable transmissions, synchronous shifting, twin countershafts and methods for control of same

Publication Date: 2024.12.24 ENVIOLO BV

AI summary

Systems and methods for controlling transmissions having CVTs are disclosed with multiple modes and gearing arrangements for range enhancements, where embodiments include synchronous shifting to allow the transmission to achieve a continuous range of transmission ratios, while minimizing “empty” cycling of the CVT during mode shifts. Embodiments provide for wide ratio range and performance and efficiency flexibility, while maximizing CVT usage through synchronous shifting.