Bearing Cooling Structure With Selective Air Nozzle Control

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Solution Overview

Problem

Existing cooling structures for spindle devices in machine tools fail to effectively manage temperature variations across multiple rolling bearings under varying operating conditions, leading to inadequate cooling and potential reliability issues due to differences in load and processing types.

Innovation Solution

A cooling structure with air nozzles, valves, and a control unit that measures temperatures across multiple rows of rolling bearings to selectively direct compressed air to the hottest bearings, using both-side and one-side exhaust passages to optimize cooling and lubrication, ensuring efficient use of limited compressed air.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If compressed air is supplied to all bearings uniformly, then cooling is provided to the bearing device, but temperature variations among different bearings are not addressed, leading to inadequate cooling of hottest bearings

Engineering Contradiction:
Improvebearing temperatureVSAvoidcooling effectiveness
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent applies local quality by providing temperature-specific cooling control to different bearing locations. Temperature measuring units monitor each bearing's temperature, and control units selectively open corresponding air nozzles based on which bearings exceed temperature thresholds. This ensures that cooling is applied locally to the hottest bearings rather than uniformly to all bearings, optimizing cooling effectiveness.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The bearing device performs self-service through automatic temperature monitoring and control. Temperature measuring units continuously monitor bearing temperatures, and control units automatically activate cooling at specific locations when temperature thresholds are exceeded, without requiring external intervention. This self-regulating system ensures reliable cooling adaptation to varying operating conditions.

Inventive Principle:
Principle #25Self-service

2Reliability

If flow rates from individual air nozzles are regulated based on fixed temperature data, then cooling is optimized for specific operating conditions, but cooling becomes inadequate when operating conditions change

Engineering Contradiction:
Improvecooling adaptabilityVSAvoidoperating condition adaptability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamics by transitioning from static, pre-determined flow rate settings to dynamic, real-time control. Temperature measuring units continuously monitor bearing temperatures under varying operating conditions, and control units dynamically adjust which air nozzles are activated and at what flow rates based on current temperature measurements. This dynamic adaptation ensures reliable cooling across different processing types and load conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system employs feedback control where temperature measuring units provide continuous temperature data to control units, which then adjust air nozzle activation and flow rates accordingly. This closed-loop feedback mechanism allows the system to adapt to changing operating conditions automatically, maintaining reliable cooling performance whether the machine tool is processing heavy loads, light loads, or different material types.

Inventive Principle:
Principle #23Feedback

3Reliability

If compressed air is discharged into a large space, then adiabatic expansion occurs and cooling efficiency increases, but the compressed air is wasted when not all bearings require cooling

Engineering Contradiction:
Improvecooling efficiencyVSAvoidcompressed air consumption
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by directing compressed air only to the specific locations where bearings require cooling. Instead of discharging compressed air into a large common space that would cool all bearings uniformly, the system selectively activates individual air nozzles corresponding to overheated bearings. This localized approach maintains high cooling efficiency for the hottest bearings while minimizing compressed air consumption by avoiding unnecessary cooling of already-cold bearings.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system implements partial action by providing cooling only to the extent necessary - specifically to the bearings that exceed temperature thresholds. Rather than applying full cooling capacity to all bearings continuously, the control units activate only the subset of air nozzles needed based on real-time temperature measurements, reducing compressed air waste while maintaining adequate cooling efficiency for the bearings that actually need it.

Inventive Principle:
Principle #16Partial or excessive action

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 allows for precise cooling of the hottest bearings, maintaining consistent temperatures across rows and improving lubrication reliability, even under varying operating conditions, thereby enhancing the overall cooling efficiency and reliability of the bearing device.

Implementation Method 1

a plurality of temperature measuring units configured to measure temperatures of the rolling bearings in the three or more rows

Methodology Applied
Scientific EffectTemperature measurement:

Implementation Method 2

the compressed air is discharged vigorously from a narrow nozzle hole into a space formed from the recess, and the compressed air is adiabatically expanded. This results in increase in the flow velocity and drop in the temperature of the compressed air

Methodology Applied
Scientific EffectAdiabatic expansion: Adiabatic Cooling

Implementation Method 3

a both-side exhaust passage between any of the outer ring spacers and the inner ring spacer which corresponds to said outer ring spacer, the both-side exhaust passage being configured to exhaust the compressed air discharged from the air nozzle toward the rolling bearings on both sides

Methodology Applied
Scientific EffectFluid flow:

Implementation Method 4

a one-side exhaust passage between any of the other outer ring spacers and the inner ring spacer which corresponds to said outer ring spacer, the one-side exhaust passage being configured to exhaust the compressed air discharged from the air nozzle toward the rolling bearing on one side

Methodology Applied
Scientific EffectFluid flow:

Data Source

PatentEP3540255B1Cooling structure for a bearing device
Publication Date: 2021.09.15 NTN CORP
  • EP3540255B1 patent drawingFigure 1
  • EP3540255B1 patent drawingFigure 2
  • EP3540255B1 patent drawingFigure 3A~3C

AI summary

A cooling structure for a bearing device according to the present invention includes: air nozzles (15) provided in a plurality of outer ring spacers (4) and configured to discharge compressed air toward inner ring spacers that face the outer ring spacers (5); valves (51) configured to regulate the compressed air discharged from the respective air nozzles (15); a control unit (52); and a plurality of temperature measuring units (53, 54) configured to measure temperatures of the rolling bearings (1). The control unit (52) uses measurement values of the temperatures obtained by the plurality of temperature measuring units (53, 54) to control the valves (51) so that the compressed air is discharged from the air nozzle (15) selected in accordance with a predetermined rule.