Toroidal Traction-Roller CVT for Higher Torque Response
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Solution Overview
Problem
Existing continuously variable transmissions (CVTs) are limited in acceleration power and mechanical response, making them unsuitable for larger vehicles and experiencing physical power transmission limits, which restrict their use to small and medium-sized vehicles with engines of 3 liters or less.
Innovation Solution
A direct shift continuously variable transmission system featuring a toroidal cavity with traction rollers, input and output disks, and a preload component that applies a radially inward force to ensure frictional contact and efficient torque transmission, allowing for compact size and efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If steel belt and cone-disk drive systems are used in CVT, then the system achieves continuous variable speed movement, but the mechanical response becomes sluggish and acceleration power is limited
Solution Approach 1:
The patent replaces the traditional steel belt and cone-disk mechanical drive system with a friction-based traction roller system. The traction rollers directly contact the input and output disks through friction, eliminating the need for steel belts and enabling direct torque transmission. This substitution of mechanical transmission method significantly improves mechanical response and acceleration power while maintaining continuous variable speed capability.
Solution Approach 2:
The patent divides the torque transmission function into multiple traction rollers that can be independently controlled. Each traction roller can be radially adjusted to change its contact position with the disks, allowing for segmented control of the transmission ratio. This segmentation enables more precise and responsive speed variation compared to the continuous but sluggish steel belt system.
2Adaptability or versatility
If traditional CVT power transmission is used, then the system is suitable for small and medium-sized vehicles with 3-liter or less engines, but there is a physical upper limit for power transmission
Solution Approach 1:
The patent changes the fundamental parameters of the power transmission system by using a friction-based traction roller mechanism instead of a steel belt system. This parameter change allows the system to handle higher torque and power levels, removing the physical upper limit that constrained traditional CVTs to small and medium-sized vehicles with 3-liter or less engines. The system can now accommodate larger vehicles and more powerful engines.
3Power
If frictional contact between traction rollers and disks is ensured through preload component, then efficient torque transmission is achieved, but the structure becomes more complex
Solution Approach 1:
The patent merges the preload function with the existing variator structure by integrating the preload component into the variator body. The preload component is positioned to directly apply radial force to the traction rollers through the variator's internal structure, eliminating the need for separate external preload mechanisms. This merging approach ensures efficient torque transmission through reliable frictional contact while minimizing additional structural complexity.
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 system provides enhanced acceleration power and mechanical response, enabling the transmission of higher torque and suitable for vehicles with larger engines, while maintaining a compact and efficient design.
Implementation Method 1
an input disk coaxially connected to the input shaft and frictionally contacting the traction roller to provide a rotational force to the traction roller
Implementation Method 2
an output disk opposed to the input disk and frictionally contacting the traction roller, the output disk being annularly rotatable by receiving the rotational force from the traction roller
Implementation Method 3
a preload component located within the variator and applying the traction roller a radially inward force so as to make frictional contact between the traction rollers and the input and output disks
Data Source
AI summary
A direct shift continuously variable transmission for a vehicle engine includes a variator having a toroidal cavity; a plurality of traction roller rotatably and radially located within the toroidal cavity; an input shaft rotatably disposed within the variator, the input shaft being adapted to receive a torque from the vehicle engine; an input disk coaxially connected to the input shaft and frictionally contacting the traction roller to provide a rotational force to the traction roller; an output disk opposed to the input disk and frictionally contacting the traction roller, the output disk being annularly rotatable by receiving the rotational force from the traction roller; and an output shaft coaxially connected to the output disk and receiving the rotational force from the output disk.