Constant Velocity Universal Joint Inner Member Axial Step Design
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Solution Overview
Problem
Conventional constant velocity universal joints face challenges in ensuring sufficient strength of the inner joint member when the thickness is reduced for weight and size reduction, especially at high operating angles and under high load torque conditions.
Innovation Solution
Incorporating an axial step portion between the inlet-side end surface of the inner joint member and the spline end portion of the shaft hole, forming a recessed end surface on a deeper side, which increases the thickness of the bottom portions of the track grooves, and setting the radial dimension of the recessed end surface to 1.5 mm or more to maintain strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the thickness of the inner joint member is reduced to decrease weight and size, then weight and size are reduced, but strength of the inner joint member deteriorates
Solution Approach 1:
The invention applies local quality by creating a recessed end surface at a specific location (the end surface of the inner joint member) while maintaining different thicknesses in different regions. The recessed end surface has a larger radial dimension than other portions, providing localized strength enhancement exactly where needed for torque transmission, while the rest of the inner joint member maintains reduced thickness for weight and size reduction.
Solution Approach 2:
The invention addresses the strength issue by transitioning from a uniform thickness design to a variable thickness design in the radial dimension. By creating a recessed end surface with increased radial dimension (1.5mm or more) compared to other portions, the design adds dimensional variation to satisfy strength requirements without increasing overall weight and size.
2Volume of moving object
If the thickness of the inner joint member is reduced to decrease size, then size is reduced, but reliability under high load torque deteriorates
Solution Approach 1:
The recessed end surface provides localized structural reinforcement at the critical location where the inner joint member interfaces with torque transmission. This local quality enhancement ensures reliable torque transmission under high load conditions while allowing the rest of the component to maintain reduced dimensions.
Solution Approach 2:
By varying the radial dimension at the end surface (creating a recessed portion with 1.5mm or more radial dimension), the invention ensures sufficient material depth for reliable torque transmission under high load, while maintaining compact overall size through reduced thickness in non-critical areas.
3Weight of moving object
If the thickness of the inner joint member is reduced to decrease weight, then weight is reduced, but strength at high operating angles deteriorates
Solution Approach 1:
The recessed end surface creates a localized thickened region that specifically addresses strength requirements at high operating angles. This local reinforcement is positioned where the inner joint member experiences maximum stress during operation, ensuring adequate strength while maintaining overall weight reduction.
Solution Approach 2:
The invention uses dimensional variation in the radial direction to solve the strength-weight contradiction. The recessed end surface provides increased radial dimension (1.5mm or more) at the critical loading region, ensuring strength at high operating angles while the reduced thickness elsewhere maintains weight reduction benefits.
Data Source
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AI summary
In order to ensure sufficient strength of an inner joint member even when the thickness of the inner joint member is reduced for achieving reduction in weight and size and even when a high operating angle is formed and high load torque is applied, a constant velocity universal joint includes: an outer joint member (10) having an inner surface (12) in which a plurality of track grooves (14) extending in an axial direction are formed; an inner joint member (20) having an outer surface (22) in which a plurality of track grooves (24) extending in the axial direction are formed while being paired with the track grooves (14) of the outer joint member (10), and an inner surface having a shaft hole (26) in which a spline (28) extending in the axial direction is formed; a plurality of balls (30) interposed between the track grooves (14) of the outer joint member (10) and the track grooves (24) of the inner joint member (20) so as to transmit torque; and a cage (40) interposed between the inner surface (12) of the outer joint member (10) and the outer surface (22) of the inner joint member (20) so as to retain the balls (30), in which the inner joint member (20) includes an axial step portion (25) provided between an inlet-side end surface (23) thereof and a spline end portion (28a) of the shaft hole (26) so as to form a recessed end surface (27) positioned on a deeper side in comparison with the inlet-side end surface (23).