Friction Roller Gear Pivot Holder Eccentricity
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Solution Overview
Problem
Friction-roller-type reduction gears face issues with intermediate roller tilt and unequal surface pressures due to torque component forces, leading to reduced durability and power transmission efficiency.
Innovation Solution
A friction-roller-type reduction gear design with pivot holders having bearing parts with eccentric pivot centers and bridging parts to stabilize the intermediate rollers, ensuring equal surface pressures and preventing torque component forces, along with a loading cam mechanism to adjust pressing forces based on transmission torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the pivot axis is arranged on the tangential line at the contact point with the sun roller, then the intermediate roller can be laid out without interference, but torque component forces are applied to the traction surface causing unequal contact surface pressures and roller tilt
Solution Approach 1:
The patent applies asymmetry by deliberately positioning the pivot axis eccentrically relative to the intermediate roller's rotational axis. The pivot axis is offset by a specific distance from the rotational axis, creating an asymmetric geometric relationship that allows the pivot axis to be located on the tangential line at the contact point with the sun roller, thereby enabling proper layout without interference while maintaining equal contact surface pressures through the bridging part structure.
Solution Approach 2:
The bridging part acts as an intermediary element that connects the pivot axis to the intermediate roller's rotational axis. This bridging structure transmits forces between the pivot holder and the intermediate roller, preventing torque component forces from being applied directly to the traction surface, thereby maintaining equal contact surface pressures and preventing roller tilt during operation.
2Ease of manufacture
If the pivot axis is positioned to avoid interference with the ring roller, then the rollers can be arranged, but relative distortion occurs at the bearing parts causing intermediate roller tilt and increased slip
Solution Approach 1:
The patent employs asymmetry by positioning the pivot axis at an eccentric location relative to the intermediate roller's rotational axis. This asymmetric arrangement allows the pivot axis to be placed on the tangential line at the contact point with the sun roller, enabling proper layout without interference from the ring roller while preventing bearing part distortion through the bridging part connection.
Solution Approach 2:
The bridging part serves as a mediator that rigidly connects the pivot axis to the intermediate roller's rotational axis. This connection prevents relative distortion between the bearing parts that support the intermediate roller, thereby maintaining proper roller alignment and preventing tilt that would otherwise occur due to the eccentric pivot axis arrangement, thus preserving power transmission efficiency.
3Reliability
If the line connecting the pivot axis and support shaft is made parallel to the tangential line, then unequal surface pressures are prevented, but interference between the arm part and ring roller occurs
Solution Approach 1:
The patent resolves this contradiction by introducing asymmetry in the form of an eccentric pivot axis position. The pivot axis is offset from the intermediate roller's rotational axis by a specific distance, allowing the line connecting the pivot axis and support shaft to be parallel to the tangential line (ensuring equal surface pressures) while the asymmetric eccentric arrangement prevents interference between the arm part and ring roller by changing the geometric relationship.
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 design prevents intermediate roller tilt and maintains stable surface pressures, enhancing power transmission efficiency and durability by ensuring equal contact pressures across the sun roller, ring roller, and intermediate rollers, regardless of torque transmission direction.
Implementation Method 1
friction-roller-type reduction gear
Implementation Method 2
loading cam mechanism configured to apply a pressing force, which is proportional to a magnitude of transmission torque
Implementation Method 3
a pair of bearing parts configured to support the rotational shaft of the intermediate roller and having a pivot center at an eccentric position from a center of the rotational shaft
Data Source
AI summary
A pivot holder of a friction-roller-type reduction gear has a pair of bearing parts configured to support a rotational shaft of an intermediate roller and having a pivot axis at an eccentric position from a center of the rotational shaft, and a bridging part configured to integrally couple the pair of bearing parts. A carrier has a holder support part configured to rotatably support the bearing parts. An interaxial distance between a center of the pivot axis and the center of the rotational shaft is equal to or smaller than a maximum radius of an outer diameter of the intermediate roller, and the center of the pivot axis is located on an applying line of a torque reaction force of transmission torque to be applied to the pivot holder.