Compliant Spindle Coupling for Accurate Driveline Error Testing
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Solution Overview
Problem
Current spindle assemblies used for measuring transmission error between the input pinion and ring gear in axle assemblies suffer from reduced accuracy and repeatability due to misalignment-induced relative motion between the encoder and differential case, necessitating an improved design for precise and automated measurement.
Innovation Solution
A spindle assembly incorporating a compliant coupling with a frame, spindle, encoder, collet assembly, and linear motor, featuring a compliant coupling mechanism with link arms and pivot plates to accommodate misalignment and enhance measurement precision, including a collet with radially movable fingers and a spring-biased expander for precise engagement with the differential case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rigid spindle assembly is used to measure transmission error, then structural stability is maintained, but misalignment causes relative motion between the encoder and differential case, reducing measurement accuracy and repeatability
Solution Approach 1:
The patent changes the rigidity parameter of the spindle assembly by introducing a compliant coupling mechanism. The compliant collar and link arms transform the rigid structure into a flexible one that can adapt to misalignment conditions, allowing the system to maintain measurement accuracy despite positional variations between the encoder and differential case.
Solution Approach 2:
The patent applies dynamics by making the spindle assembly adaptable through the compliant coupling. The link arms and compliant collar enable the assembly to dynamically adjust its configuration in response to misalignment, transitioning from a static rigid structure to a dynamic system that maintains optimal measurement conditions.
2Reliability
If the collet fingers are held in a radially outward position for engagement, then secure engagement with the differential case is achieved, but misalignment generates forces that cause relative motion and reduce measurement reliability
Solution Approach 1:
The compliant coupling acts as an intermediary between the rigid spindle components and the differential case. It absorbs and isolates the misalignment-induced forces, preventing them from transmitting to the encoder and causing relative motion, thereby maintaining measurement reliability.
Solution Approach 2:
The compliant collar and spring mechanism provide beforehand cushioning by pre-absorbing misalignment forces before they can cause harmful relative motion. This cushioning effect protects the measurement system from the adverse effects of misalignment.
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
The compliant coupling design significantly enhances the accuracy and repeatability of transmission error measurements by accommodating misalignment and maintaining precise engagement with the differential case, enabling faster and more reliable automated testing.
Implementation Method 1
The spring is disposed between the plunger and the collet mount and biases the expander toward the first expander position
Implementation Method 2
The linear motor has a motor output member that is configured to move the expander from the first expander position to the second expander position
Implementation Method 3
The encoder has a stator, which is fixed to the frame, and a rotor that is coupled to the spindle for rotation therewith
Implementation Method 4
The compliant coupling includes a first coupling member, which is fixedly coupled to the spindle, a second coupling member, which is fixedly coupled to the collet mount, a pivot plate, a pair of first link arms and a pair of second link arms
Data Source
AI summary
A spindle assembly for conducting transmission error testing between an input pinion with a ring gear of an axle assembly. The spindle assembly includes a spindle, which is rotatably disposed about a spindle axis, a collet assembly, which has a collet that is rotatably disposed about a collet axis, and a compliant coupling that couples the spindle and the collet assembly together for common rotation. The compliant coupling includes a first coupling member, which is fixedly coupled to the spindle, a second coupling member, which is fixedly coupled to the collet assembly, a pivot plate, a pair of first link arms and a pair of second link arms. The opposite ends of each first link arm are pivotably coupled to the first coupling member and the pivot plate. The opposite ends of each second link arm are pivotably coupled to the second coupling member and the pivot plate.