Cardan Joint Structure for Telescopic Torque Transmission

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Solution Overview

Problem

Conventional cardan joints are limited in their ability to absorb the variable distances and angular deviations between misaligned shafts, particularly in applications like tractor harvester heads, requiring disassembly and manual force, which is cumbersome and prone to dirt accumulation, and do not allow for telescopic coupling due to space constraints.

Innovation Solution

A cardan joint design featuring a bushing with diametrically facing cylindrical projections, a ring with orthogonal recesses and projections, and a driven tubular shaft with integral cogwheel, allowing for greater axial movement and angle absorption through complementary bearings and clearances, enabling the joint to be connected to a drive shaft and transmit torque over longer distances without disassembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional cardan joints are used to transmit torque between misaligned shafts, then torque transmission is achieved, but the ability to absorb variable distances and angular deviations is limited

Engineering Contradiction:

Improveability to absorb variable distances and angular deviationsVSAvoidrequiring disassembly and manual force

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The cardan joint incorporates a telescopic coupling mechanism that dynamically adjusts the distance between the drive shaft and driven shaft, allowing the joint to adapt to variable distances and angular deviations during operation without requiring disassembly. The telescopic elements can extend and retract to accommodate movement while maintaining continuous torque transmission.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The cardan joint is divided into modular segments including the telescopic coupling mechanism, bearings, and fork-shaped parts. This segmentation allows each component to perform its specific function independently, with the telescopic elements handling distance variation and the bearings managing angular deviations, thereby improving overall adaptability.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If telescopic coupling of greater length is used between conventional cardan joints to allow absorption of distances, then distance absorption capability is improved, but space constraints prevent implementation

Engineering Contradiction:

Improvedistance absorption capabilityVSAvoidspace required for telescopic coupling

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The telescopic coupling mechanism employs a nested structure where inner telescopic elements are housed within outer elements. This nesting arrangement allows the telescopic mechanism to achieve greater extension length while maintaining a compact retracted profile, thereby absorbing distance variations without requiring excessive space in the constrained environment.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The telescopic coupling utilizes axial dimension for distance absorption while maintaining minimal radial and lateral dimensions. By concentrating the distance absorption capability in the axial direction, the mechanism achieves effective telescopic functionality without occupying excessive space in other dimensions, resolving the space constraint issue.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If cardan drives are disassembled to allow head to change position, then positioning flexibility is achieved, but time is lost and dirt accumulation hinders operation

Engineering Contradiction:

Improvepositioning flexibilityVSAvoidtime required for disassembly and reassembly

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The continuous telescopic coupling mechanism maintains uninterrupted torque transmission throughout the positioning adjustment process. Unlike conventional joints that require complete disassembly, this mechanism allows smooth, continuous adjustment of the shaft distance and angle while the torque transmission remains active, eliminating downtime and preventing dirt accumulation during the transition.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentEP3786472B1Cardan joint connected to a drive shaft

Publication Date: 2022.10.05 MAQUINARIA AGRI Y ACCESORIOS

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AI summary

A cardan joint (1) that comprises a bushing (3) assembled on a drive shaft (11), which comprises cylindrical projections (4) facing each other and fitted in a first pair of recesses (6) of a ring (5), which in turn comprises a second pair of cylindrical projections (7) located two by two with respect to the first pair of recesses (6), on an outer surface of the ring (5), being fitted in a second pair of recesses (9) of a tubular shaft (8). A cogwheel (10) is integrally mounted on said tubular shaft (8), and configured to engage and transmit a force to a drive means.