Outer-Ring Spacer Heat Flux Sensing Under Bearing Airflow
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Solution Overview
Problem
The sensitivity of heat flux sensors in bearing apparatuses is compromised by varying air flows caused by rotation and air-oil injection, leading to delayed detection of temperature changes and potential bearing abnormalities.
Innovation Solution
The heat flux sensors are strategically positioned within the bearing apparatus, specifically in the outer-ring spacer, with optimized distances and angles relative to the bearing components and lubrication nozzles, and integrated with a cooling structure to enhance sensitivity and early detection of heat flux changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If heat flux sensor is positioned close to bearing for early temperature detection, then sensitivity to temperature change is improved, but sensor output is affected by air flow from bearing rotation and air-oil injection
Solution Approach 1:
A guide wall is introduced as an intermediary structure between the bearing and heat flux sensor. The guide wall directs the air flow generated by bearing rotation away from the sensor while allowing heat flux to pass through, thus mediating between the need for close sensor positioning and the need to avoid air flow interference
Solution Approach 2:
The solution addresses the contradiction by considering spatial dimensions - the guide wall creates a three-dimensional flow path that separates air flow from the sensor while maintaining thermal coupling, effectively using dimensional space to resolve the conflict between proximity and interference
2Object-affected harmful factors
If heat flux sensor is positioned far from bearing to avoid air flow interference, then air flow impact on sensor is reduced, but sensitivity to temperature change decreases
Solution Approach 1:
The guide wall acts as a mediator that allows the sensor to be positioned at an optimal distance from the bearing - close enough to detect temperature changes with high sensitivity, yet protected from direct air flow impact by the flow-directing function of the guide wall
3Reliability
If air-oil lubrication is used for bearing, then stable lubrication is maintained, but air flow in bearing increases affecting sensor measurement
Solution Approach 1:
The guide wall serves as a mediator that allows air-oil lubrication to function effectively for stable bearing operation while simultaneously directing the resulting air flow away from the heat flux sensor, preserving measurement accuracy
Solution Approach 2:
The harmful air flow component is extracted and directed away from the sensor by the guide wall, while the beneficial air-oil lubrication function is maintained in the bearing, separating the harmful effect from the useful function
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 configuration ensures high sensitivity of heat flux sensors even in environments with varying air flows, enabling timely detection of bearing abnormalities and improved accuracy in monitoring temperature changes.
Implementation Method 1
a heat flux sensor that senses a heat flux generated by a temperature difference between a front side and a rear side of the sensor
Implementation Method 2
The bearing for the main spindle of the machine tool is lubricated by air-oil (oil-mist) lubrication or grease lubrication
Data Source
AI summary
A bearing apparatus includes a bearing that rotatably supports a main spindle around a rotation axis, a spacer including an inner-ring spacer adjacent to an inner ring of the bearing and an outer-ring spacer adjacent to an outer ring, and a heat flux sensor provided in an inside surface of the outer-ring spacer. A distance in a direction along the rotation axis from a center of the bearing to a center of the heat flux sensor is longer than 0.5 time and shorter than one time of a dimension of the bearing in the direction along the rotation axis.