Friction Roller Reduction Gear With Cam Loading and Curved Rollers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Friction roller-type reduction gears face challenges in reducing slipping loss and improving torque transmission efficiency without increasing processing costs, while also addressing durability issues due to elastic deformation and axial loads caused by skew in needle bearings.
Innovation Solution
A friction roller-type reduction gear design featuring a sun roller with a concave curved surface, a ring roller with axially moveable elements, and a loading cam mechanism that adjusts contact surface pressures, supported by needle bearings allowing axial displacement of intermediate rollers to maintain optimal contact and reduce skew.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the outer peripheral surface of the intermediate roller is formed into a circular arc shape to reduce slipping, then rolling contact becomes point contact with reduced contact area, but contact surface pressure increases excessively and durability decreases
Solution Approach 1:
The intermediate roller is designed with a circular arc-shaped outer peripheral surface that contacts the ring roller element at a point contact, reducing slipping loss. The curvature radius is specifically controlled to balance between reducing slipping and maintaining acceptable contact pressure levels.
Solution Approach 2:
The curvature radius of the intermediate roller's outer peripheral surface is optimized as a key parameter. By adjusting this radius, the patent achieves point contact to reduce slipping while controlling the contact surface pressure to prevent excessive wear on the sun roller.
2Loss of energy
If inclination angles of intermediate roller and ring roller elements are adjusted to match, then peripheral speed difference is reduced, but processing cost increases due to complex adjustment
Solution Approach 1:
The inclination angles of both the intermediate roller and ring roller elements are set to a specific matched value (e.g., 30 degrees). This parameter optimization reduces the peripheral speed difference at the contact region, minimizing energy loss while maintaining manufacturability through standardized angle specifications.
3Ease of operation
If needle bearing is used to support intermediate roller, then rotation is facilitated, but axial load from skew causes internal gap reduction and bearing durability decreases
Solution Approach 1:
The circular arc-shaped outer peripheral surface of the intermediate roller, when combined with the needle bearing support, helps distribute loads more evenly and reduces skew during operation. This geometric design works synergistically with the needle bearing to minimize axial loading and maintain bearing internal gaps.
Solution Approach 2:
The needle bearing acts as an intermediary element between the intermediate roller and the support structure. It facilitates smooth rotation while accommodating minor misalignments and reducing the transmission of axial loads from skew to the bearing races, thereby extending bearing life.
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 design reduces peripheral speed differences, minimizes friction loss, enhances torque transmission efficiency, and improves the durability of the sun roller and bearing by maintaining consistent internal gaps in needle bearings, thus preventing excessive wear and skew.
Implementation Method 1
a rotation shaft extending to both end portions of the intermediate roller is supported to the holder via a needle bearing
Implementation Method 2
a loading cam mechanism that adjusts contact surface pressures
Implementation Method 3
The rotation of the sun roller 511 is transmitted to the ring roller 515 via the respective intermediate rollers 516
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A friction roller-type reduction gear comprising a sun roller arranged concentrically with an input shaft, a ring roller arranged concentrically with the sun roller at an outer periphery-side of the sun roller, a plurality of intermediate rollers supported to be rotatable about a rotation shaft parallel with the input shaft between an outer peripheral surface of the sun roller and an inner peripheral surface of the ring roller and configured to be in rolling contact with the outer peripheral surface of the sun roller and the inner peripheral surface of the ring roller, a coupling part configured to couple the ring roller and an output shaft, and a loading cam mechanism configured to change a contact surface pressure of a rolling contact surface of each roller, wherein the ring roller includes a pair of roller elements provided in parallel in an axial direction of the input shaft, wherein at least one of the pair of roller elements is a moveable roller element configured to be moveable axially, wherein the loading cam mechanism is arranged at only an outer end face-side of the moveable roller element in the axial direction and is configured to displace the moveable roller element towards the other roller element in correspondence to rotation torque of the input shaft, wherein the outer peripheral surface of the sun roller is a concave curved surface of which a shape of an outer edge in an axial cross-section is a concave curve, and wherein an outer peripheral surface of the intermediate roller is a convex curved surface of which a shape of an outer edge in an axial cross-section is a convex curve.