Drive Shaft Installation Coupling Unit Size Reduction
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Solution Overview
Problem
Existing drive force distributing units face challenges in reducing the size of the coupling unit due to the need for a large annular cutout portion to accurately detect the expanded state of the stop ring, which increases the axial dimension of the coupling unit.
Innovation Solution
A method of installing a drive shaft in a casing with a coupling unit that includes an inner spline teeth and an annular cutout portion, where the expanded state of the stop ring is detected by measuring the dimension between a first measuring point on the drive shaft and a second measuring point on the covering member, allowing for a reduction in the required axial dimension of the annular cutout portion and the coupling unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the annular cutout portion is formed over a large axial length to accommodate dimensional variations, then the stop ring can be stably brought into its expanded state, but the coupling unit size increases
Solution Approach 1:
The patent replaces the mechanical measurement method (measuring distance between drive shafts) with a direct dimensional measurement method (measuring dimension from drive shaft to coupling unit). This substitution eliminates the need for large axial length to accommodate variations, as the direct measurement approach is not affected by dimensional variations in the same way. The measuring dimension is directly correlated with the stop ring's expanded state without requiring a large annular cutout portion.
2Measurement precision
If the distance between right and left drive shafts is measured to detect the expanded state of the stop ring, then the expanded state can be detected, but the coupling unit requires a large axial dimension to accommodate variations
Solution Approach 1:
The patent extracts the measurement reference from the drive shaft position (which varies due to dimensional variations) and relocates it to the coupling unit itself. By measuring the dimension between a first measuring point on the drive shaft and a second measuring point on the coupling unit, the measurement is directly tied to the coupling unit's structure rather than the variable drive shaft positions. This extraction of the measurement reference eliminates the need for large axial dimension to accommodate variations.
3Manufacturing precision
If dimensional variations of the coupling unit are considered, then the distance between drive shafts varies, but this increases the required size of the annular cutout portion
Solution Approach 1:
The patent introduces a direct measurement relationship between the drive shaft and coupling unit as an intermediary measurement method. Instead of measuring the distance between drive shafts (which is affected by coupling unit dimensional variations), the measurement is taken directly from the drive shaft to the coupling unit. This intermediary measurement approach directly correlates the measured dimension with the stop ring's expanded state, making the system tolerant to dimensional variations without requiring a large annular cutout portion.
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
This method reduces the required size of the coupling unit by minimizing the variation in the distance between measuring points, enabling accurate detection of the stop ring's expanded state without increasing the axial dimension of the annular cutout portion.
Implementation Method 1
an annular groove formed in its outer circumferential surface so as to accommodate a stop ring which is elastically deformable in a radial direction
Data Source
AI summary
A method of installing a drive shaft in a casing accommodating a drive pinion and a ring gear such that the drive shaft is connected to a coupling unit accommodated in the casing, the coupling unit including: an input rotary member, an output rotary member, a clutch, and a covering member. The method including steps of: fitting the stop ring in the annular groove, and inserting the engaging shaft portion of the drive shaft into the engaging hole of the output rotary member, until the stop ring is brought into expanded state thereof in the annular cutout portion; and detecting the expanded state of the stop ring in the annular cutout portion, by measuring a dimension between first and second measuring points set respectively on the drive shaft and the covering member.