Planetary Variator With External Hinge Axis for Interference-Free Forks
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Solution Overview
Problem
Existing planetary variator designs face challenges in achieving a drill-free rolling motion and efficient torque and speed ratio variation due to complex fork design requirements, where the hinge axis intersects the central axis, leading to interference and size constraints.
Innovation Solution
The design features an eccentric hinge axis external to the central axis, allowing for non-circular rolling surfaces that ensure drill-free rolling motion, enabling a more straightforward and optimized fork construction capable of withstanding loads and varying inclination angles, with the hinge axis positioned either between or beyond the wheel portion and the central axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the hinge axis intersects the central axis (conventional design), then the planet forks can be positioned symmetrically, but the forks interfere with each other at various inclination angles and require complex design to avoid contact with ring wheel or sun wheel
Solution Approach 1:
The patent applies asymmetry by positioning the hinge axis of each planet wheel externally to the common central axis, rather than having all hinge axes intersect at the central axis. This asymmetric arrangement eliminates interference between planet forks at various inclination angles and prevents contact between forks and ring wheel/sun wheel, thereby simplifying fork design while maintaining operational capability across the full range of transmission ratios.
2Strength
If the fork size is increased to withstand forces, then load-bearing capability improves, but the forks may contact the ring wheel or sun wheel at extreme ratio values
Solution Approach 1:
By positioning hinge axes externally to the central axis, the planet forks are spatially separated from the ring wheel and sun wheel throughout the entire range of motion. This allows the forks to be sized appropriately for load-bearing requirements without risk of contact interference, even at extreme transmission ratios.
3Device complexity
If the hinge axis is positioned externally to the central axis, then fork interference is eliminated and load-bearing capability is enhanced, but the rolling surfaces become non-circular requiring precise geometric design
Solution Approach 1:
The patent employs curved rolling surfaces with specific geometric profiles on the planet wheels, ring wheel, and sun wheel. These non-circular but precisely defined curved surfaces ensure drill-free rolling motion while accommodating the external hinge axis positioning. The curvature profiles are designed to maintain continuous contact and pure rolling conditions throughout the range of motion.
4Power
If multiple planet forks are used with intersecting hinge axes, then torque capacity increases, but the forks must be designed to avoid mutual interference at all inclination angles
Solution Approach 1:
The patent positions multiple planet forks with hinge axes that are externally located relative to the central axis, creating an asymmetric arrangement that eliminates mutual interference between forks. This allows multiple planet wheels to operate simultaneously at various inclination angles without collision or mechanical interference, thereby maintaining high torque capacity with simplified fork design.
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 simplifies the fork design, enhances load-bearing capabilities, and expands the range of attainable torque and speed ratios, while maintaining the drill-free rolling motion, allowing for a more efficient and robust variable transmission system.
Implementation Method 1
The rolling surfaces of the ring wheel and the sun wheel are designed so that the drill-free rolling motion is ensured regardless of the pivotal position of the planet wheels
Data Source
Figure 1
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AI summary
The invention is related to a planetary variator applicable in a variable transmission for realizing a variable speed and torque ratio, the variator comprising a ring wheel (16), at least two planet wheels (19) and a sun wheel (17) the interaction between the wheels takes place through an essentially drill-free rolling motion of a rolling surface provided on each of the planet wheels' wheel portions (12), on rolling surfaces (20, 21) provided on the ring wheel (16) and the sun wheel (17), and wherein each planet wheel (19) is freely rotatable about a hinge axis (24) wherein said hinge axis (24) is oriented perpendicularly with respect to the plane formed by the planet wheel's rotation axis (25) and the common central axis (18), while being external to the common central axis (18).