Thrust-Sensing Bearing Compartment Assembly for Axial Strain Measurement
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Solution Overview
Problem
Conventional ball bearings in gas turbine engines without centering springs lack a convenient method to measure axial strain, making it difficult to monitor thrust balance and prevent overloading.
Innovation Solution
A thrust-sensing assembly is introduced, comprising a spacer with an outer frusto-conical portion and an inner ring, and a retaining ring with axial extensions, which includes an axial row of slots for strain gauges to measure axial thrust loads, allowing for accurate strain measurement without compromising radial load support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If ball bearings are hard-mounted without a centering spring, then the bearing assembly structure is simplified, but there is no convenient place to measure axial strain
Solution Approach 1:
A thrust-sensing assembly is introduced as an intermediary component between the bearing and bearing compartment. This assembly includes a thrust sensor that indirectly measures axial strain on the bearing, solving the measurement difficulty without complicating the bearing structure itself. The sensor assembly acts as a mediator that translates bearing thrust into measurable signals.
2Measurement precision
If a thrust-sensing assembly is added to measure axial thrust, then measurement capability is improved, but the bearing compartment axial length increases
Solution Approach 1:
The thrust-sensing assembly utilizes the radial dimension by positioning the sensor radially outward from the bearing axis. This allows measurement of axial thrust through radial measurement geometry, effectively using another dimension to solve the space constraint problem in the axial direction.
Solution Approach 2:
The thrust sensor and its mounting structure are nested within the existing bearing compartment geometry. The sensor assembly is positioned to fit within the available radial and axial space, utilizing the inner ring raceway and outer housing as natural mounting surfaces, thereby minimizing the increase in overall axial length.
3Measurement precision
If strain gauges are used on centering springs, then thrust load measurement is enabled, but the device complexity increases compared to hard-mounted bearings
Solution Approach 1:
The thrust-sensing assembly serves multiple functions: it measures axial thrust, provides structural support, and maintains bearing alignment. By combining these functions into a single integrated assembly, the design avoids the need for separate centering spring components with embedded strain gauges, thereby reducing overall device complexity while maintaining measurement capability.
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 precise measurement of axial thrust loads in hard-mounted bearings, improving thrust balance monitoring and reducing the need for extensive axial length in bearing compartments, while maintaining radial load support capabilities.
Implementation Method 1
at least one strain gauge can be mounted to one of the first and/or second side faces of one of the slots of the plurality of slots. The strain gauge can be disposed to measure an amount of tension or an amount of compression of the spacer.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A thrust-sensing assembly (82) for a bearing compartment (50B) of a gas turbine engine (10) includes a spacer (88) and a retaining ring (86). The spacer (88) includes an outer frusto-conical portion (90) and an inner ring (92). The outer frusto-conical portion (90) includes an axial row (96, 98) of a plurality of slots (94). Each slot (94) of the plurality of slots (94) includes a first rounded end (106), a second rounded end (108), a first side-face (110), and a second side-face (112) that faces the first side-face (110). The retaining ring (86) includes a plurality of axial extensions (102) with distal ends that are in contact with the outer frusto-conical portion (90) of the spacer (88).