Toric-Drive CVT Skew Limiter for Stable Gear Ratio Changes
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Solution Overview
Problem
Conventional roller position control mechanisms in Toric-drive Continuously Variable Transmissions (CVT) lack a reliable method to limit the skew angle of rollers, which affects the speed ratio between the driven and drive disks, leading to inefficiencies in gear ratio changes.
Innovation Solution
A skew limiter is introduced, comprising shaped projections that abut a control ring to limit the skew angle to a predetermined maximal angle, ensuring consistent skew angle regardless of the tilt angle, thereby maintaining a stable gear ratio across different operational positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional roller position control mechanisms are used, then the rollers can change tilt angle for speed ratio adjustment, but the skew angle cannot be reliably limited leading to inefficiencies
Solution Approach 1:
A skew limiter component is introduced as an intermediary element between the roller axle and control ring. This limiter includes shaped projections that abut against the control ring to prevent excessive skew angle movement, thereby reliably limiting the skew angle while allowing necessary tilt angle changes for speed ratio adjustment.
Solution Approach 2:
The skew limiter changes the operational parameters of the roller by imposing a geometric constraint on the skew angle. The shaped projections are configured with specific dimensions that define a maximum skew angle, transforming the uncontrolled skew parameter into a controlled parameter with predetermined limits.
2Ease of operation
If the skew angle is not limited, then the rollers have freedom of movement for tilt angle adjustment, but excessive skewing occurs leading to inconsistent gear ratio changes
Solution Approach 1:
The skew limiter acts as a mediator that permits necessary roller movement for tilt angle adjustment while blocking excessive skew angle movement. The shaped projections abut against the control ring to establish a geometric boundary, maintaining both operational freedom and ratio consistency.
Solution Approach 2:
The skew limiter is pre-configured with shaped projections that define the maximum allowable skew angle before operation begins. This preliminary geometric constraint ensures that during operation, the roller cannot exceed the predetermined skew angle, thereby preventing inconsistent gear ratio changes.
3Reliability
If a skew limiter with shaped projections is added, then the skew angle is limited to a predetermined maximal angle, but the device complexity increases
Solution Approach 1:
The skew limiting function is extracted as a separate, dedicated component (the skew limiter with shaped projections) rather than being integrated into the existing roller or control ring design. This extraction allows for a focused, simple geometric solution that adds minimal complexity while providing reliable skew angle control.
Solution Approach 2:
The skew limiter introduces a simple geometric parameter constraint through its shaped projections, which are configured with specific dimensions to define the maximum skew angle. This parameter-based approach provides reliable control without requiring complex mechanical mechanisms, maintaining relatively simple device architecture.
Data Source
AI summary
In part, skew limiter for a toric-drive CVT embodiments are disclosed. A skew limiter may include a shaped piece that limits the skew angle to a known angle notwithstanding the tilt angle of the rollers.