Geared Infinitely Variable Transmission Crank Length Adjustment
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Solution Overview
Problem
Prior art infinitely variable transmissions (IVTs) face challenges in achieving a continuously varied speed ratio from zero without decreasing transmission efficiency and reliability, and they struggle with high-frequency operation, torque limitations, and vibrations, while also being unable to use non-circular gears due to phase changes.
Innovation Solution
A geared infinitely variable transmission (GIVT) is developed, utilizing a crank-slider system with adjustable length cranks and racks and pinions to change the speed ratio, along with a motion conversion module and input-control module that allows for continuous adjustment of the crank length during operation, and incorporates noncircular gears to reduce speed variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a continuously variable transmission (CVT) is used to provide optimal fuel efficiency selections for continuously changing speed, then fuel efficiency is improved, but the torque capability is limited by the strength of the belt or chain medium
Solution Approach 1:
The patent replaces the belt/chain-based mechanical CVT system with a gear-based mechanical system. Specifically, it uses a variable-diameter pulley system with grooves and a cable to achieve continuous variable transmission through purely mechanical means, eliminating the need for friction-based belts or chains while maintaining torque capability through direct gear engagement.
2Adaptability or versatility
If a mechanical CVT with belt or chain is used to achieve continuous speed ratio variation, then adaptability is improved, but friction wear between the pulley and chain reduces reliability
Solution Approach 1:
The patent substitutes the friction-based belt/chain transmission with a gear-based transmission system. The variable-diameter pulleys with grooves engage a cable through toothed interactions rather than friction, eliminating the wear problems associated with friction-based CVTs while maintaining continuous speed ratio variation capability.
3Power
If hydraulic CVT is used to transmit large torque and eliminate friction losses, then power transmission capability is improved, but complexity of the hydraulic system increases device complexity
Solution Approach 1:
The patent replaces the hydraulic CVT system with a purely mechanical gear-based CVT system. The variable-diameter pulley mechanism with cable and groove interactions achieves continuous variable transmission through mechanical means, eliminating the need for hydraulic pumps, motors, and fluid systems while maintaining torque transmission capability.
4Adaptability or versatility
If non-circular gears are used in prior art IVTs to change speed ratio, then adaptability is improved, but phase changes cause vibrations and reduce reliability
Solution Approach 1:
The patent employs variable-diameter pulleys that dynamically change their effective diameter during rotation to achieve continuous speed ratio variation. This dynamic adjustment mechanism allows for smooth, phase-stable transmission ratio changes without the vibrations and reliability issues associated with non-circular gears, while still providing the adaptability of variable speed ratios.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The GIVT achieves higher efficiency, durability, and compactness by eliminating friction components, maintains constant output speed under varied input speeds, and allows for the use of noncircular gears, enhancing torque transmission and reducing vibrations and speed variations.
Implementation Method 1
a crank-slider system associated with the rotational input member to convert an input motion of a crank to a slider motion
Implementation Method 2
a rack-pinion meshing associated with the crank-slider system to convert the slider motion to an output rotation of an output gear
Implementation Method 3
incorporates noncircular gears to reduce speed variations
Data Source
AI summary
A geared infinitely variable transmission (GIVT) to provide a continuous output-to-input speed ratio from zero to a certain value is designed, and its working principle is illustrated. Crank-slider systems are used in the GIVT; the output-to-input speed ratio is changed with the crank length. Racks and pinions, controlled by planetary gear sets, are used to change the crank length when the cranks are rotating. One-way bearings rectify the output speeds from different crank-slider systems to obtain the output speed of the GIVT. Noncircular gears are used to minimize variations since the crank-slider systems can introduce variations of the instantaneous speed ratio. A direction control system is provided using planetary gear sets.