IVT Closed-Loop Speed Ratio Control With Time-Delay Feedback
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Solution Overview
Problem
Existing infinitely variable transmissions (IVTs) face challenges in achieving continuously varied speed ratios from zero without decreasing transmission efficiency and reliability, particularly at high frequencies and low speeds, and struggle with torque limitations and vibrations, while also requiring sophisticated electronic control systems to optimize power distribution.
Innovation Solution
The development of a control system for IVTs that includes a crank length controller and a forward speed controller, utilizing electronic components to determine desired output rotation speeds and control signals for crank length adjustments, along with an input-control module to manage motion conversion, effectively addressing speed ratio control and torque optimization through closed-loop and time-delay feedback controls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If prior art IVTs use gear contact to achieve continuously variable speed ratio, then the minimum speed ratio can be zero and variable range is larger than CVTs, but transmission efficiency and reliability decrease at high frequencies and low speeds
Solution Approach 1:
The patent applies dynamics by making the crank length adjustable during operation. The IVT system uses an actuator to dynamically change the crank length, which continuously varies the speed ratio. This dynamic adjustment mechanism allows the system to adapt to different operating conditions while maintaining reliability through controlled gear engagement, resolving the contradiction between wide speed ratio range and transmission reliability.
2Productivity
If prior art IVTs operate at high frequency, then speed ratio can be continuously varied, but control of gear engagement becomes difficult and vibrations increase
Solution Approach 1:
The patent implements feedback control through a controller that receives signals from sensors monitoring the IVT system's operation. The controller continuously adjusts the actuator position based on feedback about speed ratio, crank length, and system vibrations. This closed-loop feedback mechanism enables stable high-frequency operation by automatically optimizing gear engagement control, resolving the contradiction between productivity and ease of operation.
3Adaptability or versatility
If prior art IVTs use non-circular gears to achieve continuously variable speed ratio, then speed ratio can be varied, but phase changes occur which affect performance
Solution Approach 1:
The patent changes the parameter of crank length instead of using non-circular gears. By varying the crank length parameter through actuator control, the system achieves continuously variable speed ratio without the phase changes associated with non-circular gears. This parameter change approach maintains phase stability while providing adaptive speed ratio control, resolving the contradiction between adaptability and stability.
4Adaptability or versatility
If CVTs use friction between pulleys and belt to convert torque, then continuous speed ratio variation is achieved, but power loss is large at start-up stage with large torque and large speed ratio
Solution Approach 1:
The patent replaces the friction-based mechanical system of CVTs with a gear contact system. The IVT uses direct gear tooth contact between the non-circular gear and circular gear, eliminating the sliding friction that causes power loss in CVTs. This mechanical substitution maintains continuous speed ratio variation capability while significantly reducing energy loss, especially during high-torque start-up conditions.
Data Source
AI summary
A nonlinear closed-loop control combined with an integral time-delay feedback control is disclosed to adjust a speed ratio of an infinitely variable transmission (IVT) system. A speed ratio control for an IVT system involves a forward speed controller and a crank length controller for different speed ranges. The time-delay control is designed to reduce speed fluctuations of the output speed of an IVT with an accurate speed ratio. The speed ratio of an IVT with the disclosed control strategy can achieve an excellent tracking response for the desired constant output speed and reduce speed fluctuations of the output speed of an IVT by the time-delay feedback control.