Clearance Measurement Equipment for Gas Lubricated Dynamic Pressure Bearing of Gyro Motor

  • Tong-qun Ren
  • Zhi-rou Liu
  • Xiang-dong Xu
  • Yu Liu
  • Xiao-dong WangEmail author
Regular Paper


The clearance of gas lubricated dynamic pressure bearing of gyro motor refers specifically to small internal air gap between the rotor and stator. The clearance size is an important indicator of running performance of a motor. In this work, a dedicated clearance measurement equipment is developed. The clearance is converted to external micro displacement and measured by dual inductive probes with relative measurement principle. For this purpose, three main functional modules are designed together with corresponding electronic and pneumatic control systems. The clamp fixation module helps to support the measured bearing flexibly at the shaft end, which is conducive to protect the bearing and ensure the smoothness of force application. The force application module consists of a 3-D precision motion platform and a triaxial force sensor. It converts internal air gap to external micro displacement in cooperation with the clamp fixation module. The displacement measurement module is a 2-D precision motion platform carrying dual inductive probes. Based on theoretical analysis and practical experiments, the measurement accuracy is superior to 0.3 μm. Moreover, it realizes controllable and continuous force application, which is suitable for batch measurement.


Clearance Displacement measurement Dynamic pressure bearing Force application Gyro motor 

List of symbols


Threshold contact force for measurement


Threshold contact force for centering alignment


Total centering alignment error


Error of radial clearance measurement caused by center alignment error


Radius difference between the ball and spherical bowl of bearing


Derivation of εrc with respect to |ΔR|


Error of axial clearance measurement caused by center alignment error


Actual axial clearance


Actual radial clearance


Measured axial clearance


Measured radial clearance


Error of radial clearance caused by deflection


Error of axial clearance caused by deflection


Deflection angle of measured bearing in vertical plane


Deflection angle of measured bearing in horizontal plane



This research work was supported by National Science and Technology Major Project of China (Grant No. 2013ZX04001091), Major Project of Basic Scientific Research of Chinese Ministry (Grant No. JCYK 2016 205 A003), and the National Natural Science Foundation of China (Grant No. 51621064).


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Copyright information

© Korean Society for Precision Engineering 2019

Authors and Affiliations

  1. 1.Key Laboratory for Precision and Non-traditional Machining of the Ministry of EducationDalian University of TechnologyDalianPeople’s Republic of China
  2. 2.Key Laboratory for Micro/Nano Technology and System of Liaoning ProvinceDalian University of TechnologyDalianPeople’s Republic of China

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