Sensor-Equipped Bearing Load Estimation Drift Correction
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Solution Overview
Problem
Existing sensor-equipped wheel support bearing assemblies face challenges in accurately estimating load on vehicle wheels due to temperature-dependent drift in strain sensor outputs, especially when multiple sensors are used, leading to increased installation space, wiring, and cost requirements, as well as potential changes in sensor bonding conditions over time, which can result in significant errors in load calculation.
Innovation Solution
The proposed solution involves a wheel support bearing assembly with a load estimation processing section that includes a principal load estimating section, an amplitude processed load estimating section, and a drift amount estimating section. This setup calculates and corrects the average value of strain sensor outputs using temperature compensation and amplitude values, allowing for accurate load estimation by comparing estimated load outputs with amplitude processed load values to determine and correct for drift, without the need for additional temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple strain sensors are installed to detect load on vehicle wheels, then measurement precision is improved, but device complexity and installation cost increase
Solution Approach 1:
The patent combines multiple strain sensors into a single integrated sensor unit that detects load information. The bearing assembly incorporates strain sensors within its structure, merging the functions of multiple sensors into one cohesive component, thereby reducing installation complexity while maintaining load detection accuracy.
Solution Approach 2:
The bearing assembly serves multiple functions: it supports the wheel mechanically and simultaneously detects load information through integrated strain sensors. This multi-functionality eliminates the need for separate dedicated load sensors, reducing overall device complexity while maintaining measurement precision.
2Measurement precision
If temperature compensation is applied to correct strain sensor drift, then measurement precision is improved, but device complexity increases due to additional temperature sensors and wiring
Solution Approach 1:
The strain sensors are designed to self-compensate for temperature effects through material selection and structural design. The bearing assembly materials and sensor configurations are chosen to minimize thermal expansion and drift, eliminating the need for separate temperature compensation systems and reducing wiring complexity.
Solution Approach 2:
The patent changes the physical parameters of the bearing assembly materials and sensor construction to inherently resist temperature-induced drift. By selecting materials with matched thermal expansion coefficients and designing the sensor structure to compensate for thermal effects, the system achieves temperature stability without additional sensors or complex compensation circuitry.
3Productivity
If strain sensors are used over prolonged periods in service, then productivity is improved through continuous monitoring, but reliability decreases due to drift from vibration and impact loads
Solution Approach 1:
The bearing assembly incorporates vibration damping elements and shock-absorbing features that protect the strain sensors from vibration and impact loads before they can cause drift. This beforehand cushioning maintains sensor reliability during continuous operation while enabling prolonged productivity through continuous monitoring.
Solution Approach 2:
The patent uses composite materials in the bearing assembly construction that provide both mechanical strength and vibration isolation properties. These composite structures protect the integrated strain sensors from environmental stresses during prolonged service, maintaining output stability while enabling continuous load monitoring for improved productivity.
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 approach enables accurate load detection on vehicle wheels by reducing errors caused by temperature-dependent drift and sensor condition changes, maintaining detection accuracy over time, and eliminating the need for multiple temperature sensors, thus optimizing space, cost, and installation complexity.
Implementation Method 1
a strain gauge is pasted to an outer ring flange of the wheel support bearing assembly for detecting a strain
Data Source
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AI summary
A sensor-equipped wheel support bearing assembly capable of accurately estimating a load acting on a wheel, without the detecting accuracy deteriorated as a result of a long term use and/or a change in environment, is provided. The assembly includes a sensor unit provided in an outer member, which serves as a stationary member. The sensor unit has a strain generator and a sensor for detecting a strain occurring in the generator. A principal load estimator estimates the load acting on the wheel, with the use of an average value of a signal from the sensor, and an amplitude processed load estimator estimates the load, using amplitude of a signal wave outputted from the sensor, resulting from passage of rolling elements. A drift amount estimator estimates a drift amount of an estimated load output utilizing the average value and the amplitude, which is used to correct the estimated load.