Cardan Yoke Elastic Assembly with Interpenetrating Reliefs
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Solution Overview
Problem
Existing assemblies between a universal joint and a steering column shaft face difficulties in ensuring reliable axial and angular location during assembly, and in maintaining operation in degraded mode after damage to the elastic filtering element, with existing solutions either being complex to assemble or not providing adequate axial localization in both directions.
Innovation Solution
A simplified assembly featuring a metal part with a cylindrical hub and U-joint spider mounting legs, a resilient sleeve, and a tubular end with localization reliefs that interpenetrate to limit rotational and axial movements, allowing for easy manufacturing and assembly, and ensuring axial and angular location in both directions even after elastic sleeve deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-circular shaft end is mounted in a complementary axial hole with a tubular elastic element, then axial location and vibration filtering are achieved, but the elastic element thickness becomes non-constant causing nonlinear elastic behavior and accelerated deterioration
Solution Approach 1:
The patent introduces localization reliefs (notches or tabs) at specific locations on the shaft and complementary reliefs on the jaw that create localized contact points. This allows the shaft end to maintain a constant circular cross-section while achieving reliable axial location through the interpenetration of these localized reliefs, eliminating the need for non-circular sections and ensuring uniform elastic element thickness.
2Ease of operation
If localization reliefs are designed to interpenetrate by axial relative movement, then automatic angular indexing is achieved, but assembly complexity increases
Solution Approach 1:
The patent employs asymmetric localization reliefs (such as single-sided notches or tabs) that create a unique angular orientation when interpenetrating. This asymmetric design enables automatic angular indexing during axial assembly without requiring complex indexing mechanisms, as the reliefs naturally guide the shaft into the correct rotational position relative to the jaw.
Solution Approach 2:
The localization reliefs are pre-formed on the shaft and jaw during manufacturing, so that when the shaft is axially inserted into the jaw, the reliefs automatically engage and establish the correct angular relationship. This preliminary preparation eliminates the need for post-assembly indexing operations, enabling automatic or semi-automatic assembly processes.
3Manufacturing precision
If existing relief designs are used to ensure axial location, then axial positioning is achieved, but rotational movement limitation is insufficient
Solution Approach 1:
The patent combines multiple functions into the localization reliefs: they simultaneously provide axial location through their interpenetration geometry and limit rotational movements by creating mechanical interference when rotation exceeds the allowed range. This merged design eliminates the need for separate axial and rotational constraint mechanisms.
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
Enables automatic or semi-automatic high-rate assembly and maintains torque transmission and rotation alignment in degraded mode by limiting relative movements within the elastic sleeve's deformation limits, ensuring reliable operation even after elastic sleeve failure.
Implementation Method 1
a resilient sleeve (9) tightly fitted over the shaft (5) and into the hub (4.4)
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
An assembly is formed between a shaft (5) and a jaw (4) of a universal joint. The jaw is formed by a metal part defining a reference geometrical axis (X-X) and having one end shaped so as to define two legs (4.1) for mounting a cross member of a universal joint and clearance cutouts (4.2), a second end forming a cylindrical hub (4.4), an elastic sleeve (9) being fitted onto the shaft (5) and into the hub (4.4). The shaft has one tubular axial end which protrudes from the elastic sleeve (9) towards the legs (4.1), the tubular end of the shaft (5) having at least one locating ridge (5.3) arranged laterally opposite and at a distance from at least one complementary ridge (4.7) of the jaw, the locating ridge (5.3) and the complementary ridge (4.7) being shaped so as to be able to interpenetrate by means of a relative axial movement between the shaft (5) and the jaw (4) in order to limit the relative rotational movement between the shaft (5) and the jaw (4) about the reference axis and in order to limit the relative axial movement between the shaft (5) and the jaw (4) in a direction of interpenetration. The jaw (4) further comprises an intermediate partition (4.5) which extends perpendicularly to the reference axis (X-X) in an intermediate position between the hub (4.4) and the legs (4.1), the intermediate partition (4.5) partially closing the hub and being provided with a through-hole (4.6) for the tubular end of the shaft, wherein the tubular end of the shaft has, at least locally, a tab of material (5.4) which is folded radially outwards so as to form an axial stop engaging with the intermediate partition (4.5) in order to limit the relative axial movement between the shaft and the jaw in a direction of extraction opposite to the direction of interpenetration.