Hollow Bolt Brake Torque Sensor via Nested Strain Gauges
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Solution Overview
Problem
Existing methods for measuring brake torque in vehicle undercarriages require substantial modifications to the transmission path, leading to costly and time-consuming certification processes.
Innovation Solution
A device that measures brake torque by embedding strain gauges within a hollow bolt that transmits the torque, allowing deformation measurement without altering the transmission path, either directly attached to the bolt or indirectly through a closely fitting sensor with strain gauges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are attached to the bolt surface or a sensor is inserted into the hollow bolt, then brake torque measurement is enabled, but the bolt structure must be modified
Solution Approach 1:
The sensor is inserted into the hollow interior of the bolt, nesting the measurement device within the existing structural component. This allows the sensor to be positioned close to the deformation zone without adding external attachments that would alter the bolt's external geometry or require additional mounting holes.
Solution Approach 2:
The hollow bolt acts as an intermediary structure that accommodates the sensor while maintaining its primary function of transmitting brake torque. The bolt's hollow design provides space for the sensor without requiring modification of the bolt's material properties or structural integrity.
2Measurement precision
If the bolt is made hollow to accommodate sensors, then measurement is enabled, but manufacturing complexity increases
Solution Approach 1:
The hollow bolt serves multiple functions: it transmits brake torque mechanically and simultaneously provides accommodation space for the sensor. This multi-functionality justifies the manufacturing complexity by eliminating the need for separate sensor mounting structures or additional certification processes.
3Measurement precision
If strain gauges are attached to the bolt, then brake torque measurement is achieved, but certification costs and time increase
Solution Approach 1:
The measurement function is extracted as a separate sensor component that can be installed in the hollow bolt without modifying the bolt's load-bearing structure. This separation allows the bolt to be certified for its mechanical function independently, while the sensor is certified as a measurement device, reducing overall certification complexity and time.
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 accurate measurement of brake torque without recertification of safety-relevant components, simplifying the installation and reducing costs by utilizing strain gauges to detect deformations within the bolt, thus separating brake-induced deformation from other forces like vibrations and shocks.
Implementation Method 1
the measuring means are located in the interior of said bar-shaped member... its direct attachment to the surface of the bolt, e.g. in the form of strain gauges
Data Source
AI summary
In a measuring device for the measurement of the brake torque on an aircraft landing gear, a connecting element that is transversally loaded by the brake torque is provided with measuring elements which produce a measuring signal in function of a deformation of the connecting element. In one of two preferred variants, the measuring elements are attached to the surface of a cavity in the connecting element, and in the second preferred embodiment, a corresponding sensor is introduced into the connecting element as a whole, the sensor being so designed that deformations affect its enclosure and deform the latter as well.