Adjustable Shaft Collar Encoder Assembly for Tolerance Gap Control
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Solution Overview
Problem
In actuator assembly, encoder sensors often fail to accurately record the position of input or output shafts due to disparities caused by part sizing tolerances, leading to inefficient robot movement as the gap between sensor and target may be outside the desired range.
Innovation Solution
A shaft collar assembly with an annular body and internal bore is used to create a precise gap between encoder sensors and targets by sliding onto the output shaft and being secured with a fastener, utilizing a jig for alignment and adjustment to ensure consistent spacing despite tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional assembly methods are used without adjustment mechanisms, then the assembly process is simple and fast, but the encoder sensor positioning accuracy deteriorates due to part sizing tolerances causing gaps outside the desired range
Solution Approach 1:
The shaft collar is designed with an adjustable positioning mechanism that allows dynamic adjustment of the encoder target position relative to the encoder sensor. The collar can be moved along the output shaft to achieve the desired gap distance, transforming a static assembly into a dynamically adjustable one. This resolves the contradiction by enabling precision positioning (improving manufacturing precision) while maintaining relatively simple adjustment mechanisms (managing device complexity).
Solution Approach 2:
The invention changes the positional parameter of the encoder target by allowing the shaft collar to be adjusted along the output shaft. By modifying the distance parameter between the encoder sensor and target through collar positioning, the system achieves accurate gap control. This parameter change approach enables precise encoder positioning without requiring complex assembly mechanisms, as the adjustment is achieved through a single degree of freedom in the collar positioning.
2Reliability
If fixed positioning methods are used, then the assembly process is straightforward, but the reliability deteriorates because tolerance stack-up causes encoder targets to be outside the desired distance range
Solution Approach 1:
The shaft collar is pre-adjusted to the correct position during assembly, establishing the proper gap between the encoder sensor and target before final assembly completion. This preliminary positioning action ensures that even with tolerance variations in other components, the encoder measurement reliability is maintained. The adjustment is performed while the collar is accessible, making the process straightforward and improving ease of manufacture compared to post-assembly adjustments.
Solution Approach 2:
The shaft collar adjustment mechanism allows the assembler to self-correct positioning errors by directly adjusting the collar position. The mechanism is designed to be self-contained, requiring no special tools or complex procedures. The assembler can visually or measurably adjust the collar to achieve the desired gap, making the assembly process intuitive and improving ease of manufacture while ensuring reliable encoder positioning.
3Productivity
If tolerance stack-up is not compensated, then the manufacturing process remains simple, but the encoder gap falls outside the operational range causing inefficient robot movement
Solution Approach 1:
The invention directly addresses the gap distance parameter by allowing adjustment of the shaft collar position along the output shaft. This enables precise control of the distance between the encoder sensor and target, ensuring the gap falls within the operational range for accurate robot movement. The parameter change is achieved through a simple mechanical adjustment rather than complex manufacturing processes, maintaining manufacturing precision while improving productivity.
Data Source
AI summary
An actuator includes a housing having an input shaft, a transmission, an output shaft, a shaft collar assembly, and an encoder. The shaft collar assembly has an annular body for holding an encoder target and a fastening assembly for affixing the assembly to the output shaft. The location of the encoder target can be adjusted during assembly via an internal bore so that it is in a desired position relative to an encoder sensor when assembly is complete.