Variator Roller Control via Planet-Mediated Sun and Ring Actuation
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Solution Overview
Problem
Existing rolling-traction variators face challenges in controlling roller orientation and torque distribution due to design complexities, particularly when using a sun and ring mechanism, which can lead to fouling issues and difficulties in driving the sun effectively.
Innovation Solution
A variator design featuring a sun and ring with a planet that engages both, allowing independent control of the planet's rotation and movement along a circumferential path, preventing rotation and accommodating transverse movement, thereby controlling the tilting motion of the carrier and roller axis inclination, using an epicyclic gear set and hydraulic actuator for torque control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sun and ring mechanism is used to control roller orientation, then the variator ratio control is improved, but fouling issues occur and the sun driving becomes difficult
Solution Approach 1:
A planet carrier is introduced as an intermediary component between the sun, ring, and rollers. The planet carrier engages with both the sun and ring gears while carrying the rollers, mediating the interaction between these components. This allows the sun and ring to control roller orientation through gear engagement without direct contact between the sun/ring and rollers, preventing fouling issues while maintaining precise variator ratio control.
2Device complexity
If the planet is allowed to rotate freely, then the mechanism is simpler, but the sun and ring rotation cannot be controlled independently
Solution Approach 1:
The planet's motion is segmented into two independent components: rotation about its own axis and revolution around the sun-ring system. The planet carrier controls the revolution motion while the planet's axial rotation is controlled by its engagement with the sun and ring gears. This segmentation allows independent control of sun and ring rotation while maintaining mechanism simplicity through the natural rolling contact of the planet.
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 enables precise control of the variator ratio and torque distribution, avoiding fouling issues and allowing for efficient torque control in a torque-controlled transmission system.
Implementation Method 1
at least one roller is positioned in the space between the races and runs upon their shaped faces to transmit drive from one to the other
Implementation Method 2
the roller being mounted upon a carrier through bearings which permit the roller to spin about its axis and also to precess relative to the carrier to change the inclination of the roller axis
Implementation Method 3
a planet which engages with both the sun and the ring to control their positions
Implementation Method 4
an actuator which is operatively coupled to the planet, and an arrangement for controlling rotation of the planet independently of its engagement with the sun and the ring
Data Source
AI summary
A variator (10) has two races (12, 12) mounted for rotation about a common axis. Opposed, shaped faces (14, 18) of the races define an annular space containing at least one roller (38, 40) which runs upon the races to transfer drive between them. The roller is mounted on a carrier (42, 44) in such a way that its inclination to the common axis is able to change, to enable changes in variator ratio. The rollers and their carriers are controlled through a mechanism comprising a sun (46, 48) and a ring (50, 52) with which the carrier engages. Relative rotation of the sun and ring causes a tipping motion of the carrier (42, 44), so that the rollers steer themselves to a new inclination. To control the sun and ring, there is provided a planet (100) which engages them both. The rotational position of the carrier is controlled independently of its engagement with the sun and the ring.