Power Wrench Torque Sensing via Segmented Gearing
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Solution Overview
Problem
Power wrenches with rotatable gearing casings face challenges in connecting electric torque transducers due to increased external dimensions, affecting accessibility and handling.
Innovation Solution
A power wrench design with a separate rotatable gear casing connected via a quick coupling to the tool housing, incorporating a torque transducer within the housing to avoid sensitive electrical connections and allow for interchangeable gearing units, maintaining a compact size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a torque transducer is located in the rotatable gearing casing, then torque sensing is enabled, but the external dimensions of the gearing casing increase which adversely affects accessibility and handling
Solution Approach 1:
The patent divides the power wrench into two separate parts: a stationary housing containing the torque transducer and a rotatable gearing casing. This segmentation allows the torque sensing function to be isolated in the stationary portion, preventing the torque transducer from increasing the dimensions of the rotatable gearing casing that needs to be accessible and manageable.
Solution Approach 2:
The torque transducer is extracted from the rotatable gearing casing and placed in the stationary housing. This extraction removes the source of dimensional increase from the moving component, allowing the gearing casing to remain compact while still enabling torque measurement through the connection between the two parts.
2Measurement precision
If a torque transducer is located in the rotatable gearing casing, then torque measurement is possible, but sensitive electrical connections are required which complicates the design
Solution Approach 1:
By segmenting the device into a stationary housing with the torque transducer and a rotatable gearing casing, the patent eliminates the need for electrical connections between moving and stationary parts. The torque measurement is achieved through mechanical connection only, simplifying the electrical system.
Solution Approach 2:
The patent replaces the need for complex electrical connections with a mechanical solution. The torque transducer in the stationary housing measures torque through the mechanical interaction with the rotatable gearing casing, eliminating sensitive electrical contacts that would be required if the transducer were in the moving part.
3Volume of moving object
If the gearing casing is made compact for better handling, then accessibility improves, but space for torque transducer installation is reduced
Solution Approach 1:
The patent resolves this spatial conflict by segmenting the device into two separate housings: a compact rotatable gearing casing optimized for handling and a stationary housing that provides space for the torque transducer. This allows each component to be optimized independently for its specific function without compromising the other.
Data Source
AI summary
A power wrench including a housing, a rotation motor, a reduction gearing connecting the motor to an output shaft, and a separate gearing casing which is rotatively and detachably mounted on the housing and supporting the output shaft. The reduction gearing is divided into a first gearing stage located in the housing and a second gearing stage located in the separate gearing casing. The first gearing stage and the second gearing stage are interconnected via an intermediate spindle, and the motor is connected to the first gearing stage via a hollow drive shaft surrounding the intermediate spindle and an angle gear. A torque sensor is associated with the first gearing stage in the form of strain gauges mounted on an elastically deformable sleeve connecting a ring gear of the first gearing stage to the housing.