Toroidal CVT Thrust Bearing Oil Passage for High-Velocity Cooling
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Solution Overview
Problem
Conventional toroidal continuously variable transmissions face inefficiencies in cooling the thrust bearing due to lubricating oil colliding with obstacles, leading to reduced flow velocity and inadequate heat removal.
Innovation Solution
The design includes an oil passage with nozzles positioned to avoid collisions with the inner peripheral portions of the retainer and support, ensuring lubricating oil is supplied at high flow velocity directly to the thrust bearing, where it can effectively cool the heat-generating areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If lubricating oil is supplied to the thrust bearing, then heat removal from the contact portion is improved, but the flow velocity of the lubricating oil decreases due to collision with the power roller, support, and retainer
Solution Approach 1:
The oil passage is configured to supply lubricating oil to the thrust bearing before the oil reaches components that would cause collision and velocity reduction. This preliminary positioning ensures high flow velocity is maintained at the heat-generating contact portion, maximizing cooling efficiency
Solution Approach 2:
The patent introduces an intermediary oil passage structure that guides the lubricating oil flow from the supply source to the thrust bearing contact portion. This intermediary pathway prevents direct collision with the power roller, support, and retainer, thereby maintaining high flow velocity while still achieving effective heat removal
2Temperature
If a large amount of lubricating oil is supplied to the thrust bearing, then adequate cooling of the heat generating portion is achieved, but the quantity of lubricating oil required increases
Solution Approach 1:
The oil passage is designed to concentrate lubricating oil flow precisely at the heat-generating contact portion of the thrust bearing. This localized quality approach ensures that the oil is delivered where it is most needed for cooling, maximizing cooling efficiency per unit of oil and reducing the total quantity required
Solution Approach 2:
The patent utilizes hydraulic principles by optimizing the oil passage geometry and flow characteristics to deliver lubricating oil at high velocity and pressure directly to the thrust bearing contact portion. This hydraulic approach enhances heat transfer efficiency, allowing adequate cooling with reduced oil quantity
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 enhances the cooling efficiency of the thrust bearing by maintaining high flow velocity and reducing the amount of lubricating oil needed for effective heat removal.
Implementation Method 1
a large amount of heat is generated at a contact portion between the rolling element and the bearing groove (raceway surface) that is a surface on which the rolling element rolls. To cool such heat generating portion, it is desirable to supply lubricating oil at a high flow velocity to the heat generating portion
Data Source
AI summary
A toroidal continuously variable transmission including a power roller; a support supporting the power roller rotatably; a thrust bearing receiving a load of the power roller in a direction along a rotating axis; and an oil passage supplying lubricating oil to the thrust bearing. A surface of the power roller opposing the support includes a first bearing grooved and the support opposing the power roller includes a second bearing groove. A virtual axis of a discharge port in the oil passage reaches a bearing groove that is one of the first bearing groove and the second bearing groove. Viewed from a direction perpendicular to the rotation axis, a portion of a retainer located at a radially inner side of a retaining hole of the retainer and a portion located at a radially inner side of the bearing groove are located at sides opposite to each other across the virtual axis.