CVT Case Guide Surface for Radial Cooling Airflow
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Solution Overview
Problem
Existing continuously variable transmission (CVT) systems in utility vehicles face inefficiencies in cooling the CVT mechanism, particularly due to the lack of effective guidance and containment of cooling air within the CVT case, leading to suboptimal cooling efficiency and potential overheating.
Innovation Solution
The CVT system incorporates a centrifugal fan blade at the driving pulley and a CVT case with a guide surface portion that projects inwardly from the peripheral surface, directing cooling air along the belt and preventing axial flow, ensuring efficient cooling of the CVT mechanism by guiding air effectively between the driving and driven pulleys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is introduced into the CVT case, then cooling effect is provided to the CVT mechanism, but cooling air flows axially without effectively cooling the belt and pulleys
Solution Approach 1:
The guide surface portion is configured with a curved shape that extends in the radial direction, guiding cooling air to flow radially along the belt and pulleys. This curved surface design redirects the axial airflow into radial airflow patterns that effectively contact the hot surfaces of the belt and pulleys, converting ineffective axial flow into effective radial cooling flow.
Solution Approach 2:
The guide surface portion acts as an intermediary structure between the cooling air source and the CVT mechanism components. It mediates the airflow path by redirecting cooling air from axial direction to radial direction, ensuring the air reaches the belt and pulleys effectively for heat dissipation.
2Ease of manufacture
If the CVT case has a simple peripheral surface, then manufacturing is easier, but cooling air is not properly contained and directed within the CVT case
Solution Approach 1:
The inner surface of the CVT case is segmented into distinct functional regions: a peripheral surface portion that provides structural containment and a guide surface portion that provides airflow guidance. This segmentation allows the case to be manufactured with standard processes while incorporating the specialized guide surface geometry needed for effective cooling air direction.
Solution Approach 2:
The guide surface portion is localized to specific regions of the CVT case inner surface where airflow guidance is needed. This localized modification maintains the overall simplicity of the case structure for easy manufacturing while adding complex geometry only where required for cooling air containment and direction.
3Device complexity
If cooling air flows axially through the CVT case, then air circulation is simple, but cooling effectiveness on belt and pulleys is insufficient
Solution Approach 1:
The guide surface portion utilizes curved geometry to transform axial airflow into radial airflow. The curved surface redirects the cooling air to wrap around and contact the belt and pulleys, increasing the surface area of thermal contact and improving heat transfer effectiveness without adding complex external cooling systems.
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 CVT mechanism by ensuring adequate airflow along the belt and pulleys, preventing axial air flow and maintaining optimal operating temperatures, thus improving the reliability and performance of the CVT system.
Implementation Method 1
a centrifugal fan blade disposed at the driving pulley
Data Source
AI summary
A continuously variable transmission includes: a CVT mechanism including a driving pulley, a driven pulley, an annular belt wound around the driving pulley and the driven pulley, and a centrifugal fan blade disposed at the driving pulley; and a CVT case that defines an internal space accommodating the CVT mechanism. An inner surface of the CVT case includes: a peripheral surface portion that covers the CVT mechanism from an outer side in a radial direction orthogonal to an axial direction of the driving pulley; and a guide surface portion that projects toward an inner side in the radial direction from the peripheral surface portion.