Toroidal CVT Back Surface Cylinder Wall for Gear Placement
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Solution Overview
Problem
In toroidal continuously variable transmissions for aircraft electric power generating devices, the integration of gear at the outer peripheral portion of the input disc increases the outer diameter, leading to higher oil agitation loss and reduced efficiency, while separate disc configurations compromise reliability due to increased axial deformation.
Innovation Solution
A double-cavity-type toroidal continuously variable transmission design featuring separate input and output discs with back surface cylinder walls allows for efficient placement of the input gear and bearings between the discs, reducing oil agitation loss and maintaining reliability by minimizing size increase and axial deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the gear is provided at an outer peripheral portion of the input disc, then the gear can be disposed, but the outer diameter of the gear increases, so that the circumferential speed of the gear increases and oil agitation loss increases
Solution Approach 1:
The gear is moved from the outer peripheral portion (radial dimension) to the inner peripheral portion (axial dimension) by utilizing the back surface cylinder wall space. This dimensional transition allows the gear to be disposed without increasing the outer diameter, thereby reducing circumferential speed and oil agitation loss while maintaining ease of gear disposal
2Ease of manufacture
If the two discs at the axially central portion are formed as separate members, then the gear can be disposed between the discs, but the back surfaces of both discs are supported by bearings, so that deformation of the discs increases and reliability decreases
Solution Approach 1:
The input disc is segmented into a disc body portion and a back surface cylinder wall portion that are integrally formed. The back surface cylinder wall protrudes from the back surface and provides structural support, allowing the gear to be disposed between separate discs while the integrated wall structure prevents excessive deformation and maintains reliability
3Weight of stationary object
If the two discs adjacent to each other at the axially central portion are integrally formed, then the transmission can be configured with small size and light weight, but the gear is provided at an outer peripheral portion, so that the outer diameter increases and efficiency decreases
Solution Approach 1:
The gear disposal location is changed from the outer peripheral portion (radial dimension) to the inner peripheral portion (axial dimension) utilizing the back surface cylinder wall space. This allows the discs to remain integrally formed for compact size and light weight while the gear is positioned to reduce outer diameter and oil agitation loss, resolving the efficiency contradiction
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 effectively reduces oil agitation loss and maintains high reliability by optimizing gear placement and support structures within the transmission, enhancing the efficiency and durability of the electric power generating device.
Implementation Method 1
a power roller that is brought into contact with opposed curved concave surfaces of both discs at high pressure
Data Source
AI summary
In a continuously variable transmission including: a first transmission unit including a first input disc and a first output disc disposed coaxially and a power roller tiltably interposed between these discs; and a second transmission unit disposed coaxially with the first transmission unit, including a second input disc and a second output disc disposed coaxially and a second power roller tiltably interposed between these discs, and disposed such that a back surface of the second input disc is opposed to a back surface of the first input disc, a tubular back surface cylinder wall is provided on each of the back surfaces of the first input disc and the second input disc so as to project therefrom.