Wheel Bearing Acceleration Sensor Mounting for Brake Load Detection
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Solution Overview
Problem
Existing vehicle wheel rolling bearing units fail to accurately measure translational acceleration on a tire when the brake is applied, leading to inaccuracies in load detection, and require costly reattachment of acceleration sensors during tire replacement.
Innovation Solution
A vehicle wheel supporting rolling bearing unit with at least three acceleration sensors fixed on a virtual plane orthogonal to the rotation side bearing ring member, allowing for the measurement of translational acceleration by subtracting centrifugal acceleration from sensor outputs, and a power generation system to supply power to the sensors, enabling wireless communication of load data without the need for direct tire-side sensor reattachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an acceleration sensor is directly provided on the tire, then the load acting on the tire can be obtained regardless of brake operating state, but it is necessary to re-attach the sensor during tire replacement resulting in cost increase
Solution Approach 1:
The patent uses the bearing unit as an intermediary carrier to mount the acceleration sensor. Instead of attaching the sensor directly to the tire, it is fixed to the bearing unit which remains stationary during tire replacement. This mediator approach allows the sensor to indirectly measure tire load while avoiding the need for reattachment when tires are changed.
Solution Approach 2:
The bearing unit serves dual purposes: it supports the wheel rotation function and simultaneously serves as a mounting platform for the acceleration sensor. This self-service approach eliminates the need for separate sensor mounting structures and avoids reattachment costs during tire maintenance.
2Ease of manufacture
If a load sensor is provided in the rolling bearing unit, then the load acting on the tire can be obtained, but the detected load does not match the actual load on the tire when brake is acting
Solution Approach 1:
The patent introduces acceleration sensors as intermediary devices that measure translational acceleration of the bearing unit. By combining this acceleration data with wheel rotation data, the system indirectly calculates tire load while compensating for brake force effects, achieving accurate measurement without direct load sensing on the tire.
Solution Approach 2:
The patent replaces direct mechanical load sensing with a combination of acceleration sensing and rotational measurement. Instead of using a load sensor that directly measures force, it uses acceleration sensors to capture motion dynamics and computationally derives the load information, substituting mechanical measurement with a hybrid sensor approach.
3Measurement precision
If acceleration sensors are arranged to detect translational acceleration of the bearing unit, then the load acting on the tire can be obtained regardless of brake state, but the sensor arrangement becomes complex
Solution Approach 1:
The patent strategically positions acceleration sensors at specific locations on the bearing unit where they can effectively detect translational acceleration. By optimizing the local placement of sensors rather than using a complex array throughout the system, it achieves accurate load measurement with minimal sensor complexity.
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 accurate measurement of translational acceleration and load on the tire regardless of brake state, reducing costs by eliminating the need for frequent sensor reattachment and improving assembly and handling of the bearing unit.
Implementation Method 1
the control unit subtracts centrifugal acceleration from the sensor outputs to obtain translational acceleration
Data Source
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AI summary
A wheel supporting rolling bearing unit in which a first acceleration sensor 52, a second acceleration sensor 53, and a third acceleration sensor 54 are fixed on a virtual plane of a rotating-side bearing ring member orthogonal to a central axis of the rotating-side bearing ring member. The first acceleration sensor 52 and the second acceleration sensor 53 are disposed on a virtual line passing through the center of rotation of the rotating-side bearing ring member, at positions equidistant from the center of rotation, with the respective directions of detection thereof oriented in radial directions of the rotating-side bearing ring member and oriented in mutually opposite radial directions. The third acceleration sensor 54 is disposed with the direction of detection thereof in an orientation which is not parallel to the direction of detection of either the first acceleration sensor 52 or the second acceleration sensor 53. Translational accelerations acting on the acceleration sensors are measured, and a load acting on a tire is determined regardless of the operating state of a brake.