Traction Drive Speed Reducer with Preloaded Rolling Bearings
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Solution Overview
Problem
Conventional traction drives face challenges in achieving a wide range of reduction ratios while minimizing vibration, noise, and slippage, particularly due to the limitations of gear-based systems and the increased slip ratio with higher output torque in bearing-modified speed reducers.
Innovation Solution
A speed increasing/decreasing apparatus is designed with a configuration that includes a first and second rotary shaft, rolling bearings, a preload unit, and a load-receiving part, where the preload force is transmitted through the bearings to ensure torque transmission without relative movement, allowing for a wide range of reduction ratios while preventing slippage and minimizing vibration and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a gear-based speed increasing/decreasing apparatus is used, then a wide range of reduction ratios can be achieved, but the levels of noise and vibration increase
Solution Approach 1:
The patent replaces the gear-based mechanical transmission system with a traction drive system using rolling bearings. The input shaft and output shaft are connected through rolling bearings that utilize frictional force and elastic deformation for torque transmission, eliminating gear meshing and its associated noise and vibration while achieving a wide range of reduction ratios through variable slip ratios.
Solution Approach 2:
The patent changes the operational parameters of the rolling bearing system by applying controlled preload forces and utilizing elastic deformation of the bearing components. By varying the slip ratio between the inner and outer rings of the rolling bearings, the system achieves different reduction ratios without mechanical gear engagement, thereby maintaining low noise and vibration levels across a wide range of operation.
2Force
If the slip ratio is increased to achieve higher output torque in a bearing-modified speed reducer, then torque transmission capability improves, but slippage between components increases
Solution Approach 1:
The patent applies preliminary preload forces to the rolling bearings before torque transmission begins. This preliminary action creates initial contact pressure and elastic deformation in the bearing components, establishing a foundation for reliable torque transmission. The preload ensures that when high torque is required, the components maintain sufficient frictional force to prevent excessive slippage while still allowing the necessary slip ratio for torque transmission.
Solution Approach 2:
The patent utilizes the dynamic characteristics of elastic deformation in the rolling bearing components to adapt to varying torque requirements. The system dynamically adjusts the slip ratio based on the applied load, with the elastic properties of the bearing components allowing controlled deformation that maintains optimal contact pressure and frictional force across different operating conditions, preventing both excessive slippage and component damage.
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 apparatus effectively achieves a wide range of reduction ratios while suppressing vibration and noise, and preventing slippage, outperforming gear-based systems in terms of noise and vibration reduction.
Implementation Method 1
a first rolling bearing that is disposed between the first rotary shaft and the case and that supports the first rotary shaft in such a manner as to be rotatable; a second rolling bearing that is disposed between the supporting part and the first rotary shaft and that supports the first rotary shaft and the second rotary shaft in such a manner as to be rotatable relative to each other
Implementation Method 2
a preload unit that is provided on the case and that applies a preload force such that the second rotary shaft is pushed to the first rotary shaft side... since the outer ring is stationary due to frictional force acting upon the case
Data Source
AI summary
A first rotary shaft and a second rotary are rotatable around a rotation axis. The second rotary shaft has a cylindrical supporting part that covers an end section of the first rotary shaft. A case supports the first and second rotary shafts. A first rolling bearing is disposed between the first rotary shaft and the case and rotatably supports the first rotary shaft. A second rolling bearing is disposed between the supporting part and the first rotary shaft and supports the first rotary shaft and the second rotary shaft such that they are rotatable relative to each other. A transmission part of the second rotary shaft transmits to the second rolling bearing a preload force that pushes the second rotary shaft to the first rotary shaft side. A load-receiving part of the case receives the preload force transmitted from the second rolling bearing to the first rolling bearing.