Variator Roller Precession Control via Carrier Rotation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rolling-traction variators face limitations in controlling roller orientation, which affects the variator drive ratio, due to constraints in the choice of castor angle and potential fouling of components within the variator cavity.
Innovation Solution
A continuously variable ratio device with a carrier that can rotate about a non-parallel axis, allowing the roller to precess relative to the carrier, enabling the precession axis to change orientation and thus varying the drive ratio, while avoiding fouling through a gearing arrangement that includes a sun and ring mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the roller is constrained to precess about a fixed precession axis relative to the carrier, then the structure is simpler, but the flexibility in choosing the castor angle is limited and component fouling may occur
Solution Approach 1:
The precession axis is made dynamic by allowing the carrier to rotate about the variator axis, so that the precession axis orientation changes with carrier rotation. This enables the castor angle to be varied continuously during operation, providing adaptability while using a relatively simple rotational mechanism
Solution Approach 2:
The carrier serves multiple functions: it supports the roller, defines the precession axis orientation, and rotates about the variator axis to change the castor angle. This multi-functionality achieves flexibility without requiring separate mechanisms for each function
2Ease of operation
If the carrier rotates about the variator axis to change precession axis orientation, then control over drive ratio is improved, but the device complexity increases
Solution Approach 1:
The carrier rotation is driven by the interaction between the roller and the races through the precession mechanism itself. The roller's precession motion, caused by the speed difference between the carrier rotation and the roller spin, automatically drives the carrier rotation, eliminating the need for external control mechanisms
Solution Approach 2:
The precession mechanism acts as an intermediary that couples the carrier rotation to the roller orientation control. The roller's precession motion mediates between the carrier's rotational movement and the roller's spin, translating carrier rotation into controlled changes in drive ratio
3Reliability
If the precession axis is fixed relative to the carrier, then the mechanism is simpler, but torque control is less effective
Solution Approach 1:
The dynamic orientation of the precession axis, varying with carrier rotation, enables the steering effect to be optimized at different operating conditions. This improves torque control effectiveness by allowing the precession axis to be optimally oriented relative to the applied torques, while the mechanism remains relatively simple
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 solution provides greater control over the relationship between carrier displacement and variator drive ratio, offering improved torque control and flexibility in choosing the castor angle, reducing the risk of component fouling and enhancing variator performance.
Implementation Method 1
the roller being able to precess about a precession axis which is non-parallel to the roller axis and thereby to change the angle between the roller axis and the variator axis
Data Source
AI summary
A continuously variable ratio device (“variator”) is disclosed in which a pair of rotary races (252, 254) is mounted for rotation about a common variator axis (218). Drive is transferred from one race to the other through at least one roller (200) running upon them. The drive ratio is variable by virtue of precession of the roller about a precession axis (228). Precession results in a change in angle between the roller axis and the variator axis and a corresponding change in drive ratio. In accordance with the invention, the roller (200) is coupled to a carrier (214) in a manner which permits it to precess relative to the carrier (214). The carrier itself is rotatable about a carrier axis (226) which is non-parallel to the precession axis. Rotation of the carrier (214) about the carrier axis serves to change the orientation of the precession axis (228) and is accompanied by a change in variator drive ratio.