Multi-mode Infinitely Variable Transmission Power Distribution
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Solution Overview
Problem
Existing infinitely variable transmissions face limitations in efficiently utilizing both mechanical and infinitely variable power sources, leading to increased wear and the need for larger, more powerful infinitely variable power sources, especially in modes like powered-zero and creeper modes, due to excessive speed matching requirements.
Innovation Solution
The implementation of a multi-mode infinitely variable transmission (MIVT) using a combination of planetary and double planetary gear sets, along with strategically placed clutches and brakes, allows for controlled power distribution between engine and infinitely variable power sources, enabling heavier mechanical path utilization while avoiding excessive infinitely variable power source speeds in certain modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a traditional planetary gear set is used to sum rotational power from engine and electric machine, then power transmission is achieved with infinitely variable effective gear ratio, but the maximum practical speed of variable power sources is limited
Solution Approach 1:
The transmission system is segmented into two separate planetary gear sets: a first planetary gear set that handles engine power transmission, and a second planetary gear set that handles electric machine power transmission. This segmentation allows each power source to operate independently within its optimal speed range, resolving the contradiction between speed limitations and power transmission efficiency.
Solution Approach 2:
A mechanical coupling mechanism acts as an intermediary between the two planetary gear sets, enabling power summation without requiring direct speed matching between the engine and electric machine. This intermediary allows each power source to operate at different speeds while still achieving effective power combination at the output.
2Reliability
If heavier mechanical path utilization is implemented, then wear on infinitely variable power sources is reduced, but the transmission system complexity increases
Solution Approach 1:
The transmission system is divided into two independent planetary gear sets, each handling a specific power source. This segmentation allows the mechanical path from the engine to be optimized for durability and reduced wear, while the electric machine path handles variable speed requirements, thereby improving overall reliability without excessive complexity.
Solution Approach 2:
The dual planetary gear set configuration provides multi-functionality: it can operate in engine-only mode, electric machine-only mode, or combined mode. This universality allows the system to utilize the durable mechanical path for engine power while maintaining the flexibility to use the electric machine path when needed, achieving both durability and adaptability.
Data Source
AI summary
An infinitely variable transmission includes a clutch, a brake and a first planetary gear set, including first and second components, and a double planetary gear set, including input and output components and additional third and fourth components. The first component receives power from an engine. The double planetary set sums mechanical power from the first planetary set and an infinitely variable power source (“IVP”). The third component receives mechanical power from a IVP. The second component directly transmits power to the input component. The clutch directly controls power transmission between the first and second components. The brake engages the fourth component to stop its rotation. The output component receives mechanical power directly from the input component and the fourth component. During operation of the engine, controlled actuation of the brake and the clutch causes the output component to be powered by the infinitely variable power source but not by the engine.