Pre-tensioned Roller Bearing Mounting with Real-time Rolling Torque Feedback
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Solution Overview
Problem
Current methods for setting a defined preload in wheel bearings, particularly in high-performance vehicles, are inaccurate due to various influences such as friction coefficients, tolerances, and thermal expansion, leading to iterative and time-consuming processes for achieving optimal rolling moment.
Innovation Solution
Measuring the rolling moment in real-time during nut tightening and using a device that rotates the shaft while measuring the rolling moment, allowing for precise control of the preload by determining the target rolling moment difference at room or operating temperature, and utilizing a deformable spacer to define the initial tightening torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the nut is tightened to a specific torque to set the preload, then the process is simple, but the preload accuracy is extremely disadvantageous and varies over a very wide range
Solution Approach 1:
The patent employs a feedback mechanism by measuring the rolling moment during nut tightening and using this measurement to control the preload setting process. The rolling moment sensor provides real-time feedback that allows the system to adjust the tightening process to achieve the target preload value, thereby resolving the contradiction between simplicity and accuracy.
Solution Approach 2:
The patent replaces the purely mechanical torque-based preload setting with a measurement and control system that uses rolling moment sensing. This substitution of mechanical intuition with measured physical quantities enables precise preload control while maintaining process simplicity through automation.
2Measurement precision
If the rolling moment is measured before and after tightening to check preload, then the preload can be verified, but the work amount increases considerably and the process becomes time-consuming
Solution Approach 1:
The patent implements continuous measurement of rolling moment during the entire nut tightening process, rather than discrete measurements before and after. This continuous monitoring allows the preload setting to be completed in a single continuous operation, eliminating the need for iterative testing and significantly reducing the time required.
Solution Approach 2:
The patent performs the rolling moment measurement concurrently with the tightening process itself, rather than as a separate subsequent step. By integrating the measurement into the tightening operation, the verification is accomplished preliminarily during the process, eliminating additional time-consuming steps.
3Productivity
If the rolling moment is measured instantaneously to determine preload, then the measurement is quick, but the coefficient of thermal expansion is completely ignored leading to inaccuracies
Solution Approach 1:
The patent accounts for thermal effects by considering the coefficient of thermal expansion in the preload calculation. The system adjusts the target rolling moment value based on temperature conditions, thereby maintaining preload accuracy despite thermal expansion variations that would otherwise compromise precision.
4Manufacturing precision
If a deformable spacer is used to define initial tightening torque, then the preload can be precisely controlled, but the device complexity increases
Solution Approach 1:
The patent introduces a deformable spacer as an intermediary element between the nut and the bearing inner ring. This spacer serves as a mediator that translates the tightening torque into a controlled preload through its deformation characteristics, enabling precise preload control while simplifying the overall device by avoiding complex measurement and control systems.
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
Enables precise and efficient setting of the optimal preload, reducing the need for iterative processes and ensuring the preload is maintained accurately, even considering thermal expansion, thereby improving the accuracy and efficiency of the prestressing process.
Implementation Method 1
a deformable spacer ring (16) with a material that is deformable and an excess over the distance between the two bearing seats (18, 19)
Implementation Method 2
the coefficient of thermal expansion of the parts is completely ignored
Data Source
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AI summary
A method for mounting mutually preloaded rolling bearings (1) in an arrangement with a positive pressure angle (14), the outer rings (7", 8") of which are mounted in a support (17) and the inner rings (7', 8') of which are mounted on a shaft (1), with a nut (6) that can be screwed onto the shaft engaging the inner ring (8') of the second rolling bearing (8), is intended to allow for precise and rapid adjustment of the preload. For this purpose, the support (17) and shaft (1) are rotated relative to each other, and the rolling torque is continuously measured in real time, thereby generating a rolling torque difference. When a predetermined target value of the rolling torque difference is reached, the rotation of the nut (6) is stopped, and the desired preload is achieved. In the associated device, the shaft (1) is rotated, and the support (17) and nut (6) are each connected to the frame of the device via a torque sensor (33, 40).