Toroidal CVT Disc Shrouds Reduce Oil Agitation Loss
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Solution Overview
Problem
Existing toroidal continuously variable transmissions face issues with increased oil agitation loss and reduced reliability due to high circumferential speed of gears, leading to decreased efficiency in electric power generation devices for aircraft.
Innovation Solution
A double-cavity-type toroidal continuously variable transmission design with separate input discs at the axially central portion and an input gear between their back surfaces, along with disc shrouds to reduce oil agitation and maintain compact size, addresses the problem by decreasing the outer diameter of the input gear and preventing extra oil from contacting the discs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If two discs at the axially central portion are integrally formed, then the entire transmission can be configured with a small size and light weight, but the outer diameter of the gear increases causing increased circumferential speed and oil agitation loss
Solution Approach 1:
The input discs are divided into separate members rather than being integrally formed. This segmentation allows the gear to be positioned between the discs with reduced outer diameter, thereby decreasing circumferential speed and oil agitation loss while maintaining compact overall dimensions through optimized spatial arrangement.
2Loss of energy
If two discs at the axially central portion are formed as separate members, then the gear outer diameter can be reduced to suppress circumferential speed increase, but deformation of the discs increases causing reduced reliability
Solution Approach 1:
The first and second input discs are connected by a connecting portion to form an integrated structure that maintains rigidity while allowing the gear to be positioned between them. This merging provides mutual support to the discs, preventing excessive deformation and maintaining reliability while keeping the gear outer diameter reduced.
3Power
If high gear ratio is achieved by increasing disc rotation speed, then power transmission capability improves, but oil agitation resistance increases causing decreased fuel efficiency
Solution Approach 1:
The patent introduces shrouds that cover the side surfaces and outer peripheral surfaces of the input and output discs, creating a three-dimensional containment structure. This dimensional addition restricts oil movement paths and reduces oil agitation caused by high-speed rotation, thereby decreasing energy loss and improving fuel efficiency while maintaining high power transmission capability.
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
This configuration reduces oil agitation loss and resistance, enhancing the reliability and efficiency of the electric power generation device while maintaining a compact size, thereby improving fuel efficiency and oil management.
Implementation Method 1
a power roller that is brought into contact with opposed curved concave surfaces of both discs at high pressure
Implementation Method 2
by covering the input discs and the output discs with the disc shrouds, extra oil that is present around both discs is prevented from coming into contact with the surfaces of the discs
Implementation Method 3
a power roller that is brought into contact with opposed curved concave surfaces of both discs at high pressure
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
In a continuously variable transmission including: a first transmission unit including a first input disc and a first output disc; and a second transmission unit disposed such that a back surface of a second input disc is opposed to a back surface of the first input disc, an input gear shroud covering an input gear disposed between the back surfaces of the first and second input discs, a first input disc side surface shroud integrally provided to a first input disc support supporting the first input disc on a housing of the continuously variable transmission, and a second input disc side surface shroud integrally provided to a second input disc support supporting the second input disc on the housing of the continuously variable transmission, are provided.