Self-Aligning Driven Clutch for CVT Belt Misalignment
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Solution Overview
Problem
Existing continuously variable transmissions (CVTs) face issues with belt misalignment between the drive and driven clutches, leading to enhanced drag, poor performance, and undue wear on the belt, particularly when adjusting from high gear ratios to idle.
Innovation Solution
A self-aligning driven clutch system with a self-aligning return system that includes a driven post sleeve and a driven sleeve biasing member, allowing the driven clutch to follow the axial movement of the drive clutch, maintaining belt alignment throughout the shift ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a floated driven clutch is used to allow axial movement to follow belt movement, then belt alignment is improved during gear ratio adjustment, but the clutch may not follow the belt properly during coast stop operations, leading to misalignment
Solution Approach 1:
A follower arm is introduced as an intermediary mechanism between the belt and the driven clutch. The follower arm has a follower tip that contacts the belt and a driven clutch contact surface that acts on the driven clutch, translating belt movement into controlled axial movement of the driven clutch. This intermediary mechanism ensures reliable following behavior during coast stop operations while maintaining belt alignment during gear ratio adjustment.
Solution Approach 2:
The follower arm is biased by a spring to automatically follow the belt's axial movement without requiring external control systems. The spring provides the necessary force for the follower tip to maintain contact with the belt and transmit its movement to the driven clutch, enabling the system to self-regulate alignment during various operational conditions including coast stops.
2Device complexity
If the driven clutch is fixed axially, then structural simplicity is maintained, but belt misalignment occurs during gear ratio adjustment from idle to full speed
Solution Approach 1:
The driven clutch transitions from a fixed axial position to a dynamically adjustable position through the follower arm mechanism. The driven clutch can now move axially in response to belt movement during gear ratio adjustment, while the spring provides a restoring force to return it to its home position when not in use, achieving both adaptability and structural efficiency.
Solution Approach 2:
The driven clutch assembly is segmented into movable and fixed components. The driven clutch body is separated from the fixed housing, allowing it to move axially on the driven post while the housing remains stationary. This segmentation enables the clutch to follow belt movement without requiring the entire assembly to be movable, maintaining structural simplicity while achieving alignment.
3Manufacturing precision
If the driven clutch follows the belt axially, then belt alignment is maintained, but additional components are required increasing device complexity
Solution Approach 1:
The follower arm mechanism is integrated with the driven clutch assembly, combining the alignment function with the existing clutch structure. The follower arm utilizes the driven post and housing as mounting points, merging multiple functions (alignment, torque transmission, and return) into a unified assembly that minimizes the number of separate components.
Solution Approach 2:
The follower arm serves as a compact intermediary mechanism that achieves belt alignment with minimal components. Rather than using a complex actuation system, the simple lever arm with spring bias provides efficient alignment while adding only one moving component (the follower arm itself) to the system.
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 self-aligning return system ensures proper belt alignment at both idle and high gear ratios, reducing drag, improving performance, and extending belt life by minimizing misalignment-induced wear.
Implementation Method 1
The driven sleeve biasing member is positioned to exert a biasing force on the driven post sleeve relative to the driven post to a home belt alignment position
Implementation Method 2
The movable sheave assembly is configured to move axially on a post as rotational speed and centrifugal forces increase and decrease
Data Source
AI summary
A self-aligning driven clutch is provided that includes a self-aligning return system. The self-aligning return system includes a driven post sleeve and a driven sleeve biasing member. The driven post sleeve is slidably mounted on a driven post in an axially movable arrangement. The driven sleeve biasing member is positioned to exert a biasing force on the driven post sleeve relative to a driven post to a home belt alignment position. A driven fixed sheave is mounted on the driven post sleeve of the self-aligning return system in an axially fixed arrangement. A driven moveable sheave is slidably mounted on the driven post sleeve of the self-aligning return system in an axially movable arrangement. A driven moveable sheave actuation system moves the driven movable sheave in relation to the driven fixed sheave on the driven post sleeve based on at least a force experienced by the self-aligning driven clutch.