Linear Drive Cardan Joint Clearance Fit Design

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing linear drives face challenges in achieving long service life due to tension-related deformations and resulting frictional forces, which can lead to reduced performance and increased risk of leaks from dust and dirt ingress.

Innovation Solution

The linear drive incorporates a cardan joint with loose-fitting elevations and recesses to compensate for play, avoiding tension and deformations, and features a bearing plate with a continuous recess for air pressure equalization and heat dissipation, ensuring a hermetically sealed and stable design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a rigid connection is used between the linear drive and the device to be driven, then structural stability is improved, but tension and deformations occur reducing service life

Engineering Contradiction:
Improvestructural stabilityVSAvoidservice life
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The connection type is changed from rigid to cardan joint with clearance fit, transforming the mechanical connection parameters to allow angular compensation while maintaining stability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The cardan joint acts as an intermediary element between the linear drive and the device to be driven, compensating for misalignments and preventing tension transmission

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a cardan joint with clearance fit is used to avoid tension, then service life is improved, but structural stability decreases

Engineering Contradiction:
Improveservice lifeVSAvoidstructural stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The connection parameters are optimized by using elevations with specific dimensions that provide sufficient rigidity while maintaining the clearance fit necessary for cardan joint functionality

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the linear drive is hermetically sealed to prevent leaks, then reliability is improved, but heat dissipation capability deteriorates

Engineering Contradiction:
Improveprotection against dust and dirtVSAvoidheat dissipation
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

A bellows structure is used to create a hermetic seal while allowing for thermal expansion and maintaining pressure equalization, enabling both protection and heat dissipation

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The bellows acts as an intermediary flexible membrane that separates the internal drive components from the external environment while allowing thermal energy to dissipate

Inventive Principle:
Principle #24Intermediary (Mediator)

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 design enhances the service life by reducing frictional forces, preventing leaks, and improving heat dissipation, resulting in a more reliable and durable linear drive system.

Implementation Method 1

two joint parts connected to one another having second elevations projecting in the transverse direction to the axis of the spindle, in particular one elevation being formed on each of the joint parts, with each of the joint parts having a recess into which in each case a first elevation is at least partially inserted, in particular in each case by means of a clearance fit

Methodology Applied
Scientific EffectClearance fit:

Implementation Method 2

bearing plate with a continuous recess for air pressure equalization

Methodology Applied
Scientific EffectAir pressure equalization: Pressure Gradient

Implementation Method 3

bearing plate with a continuous recess for air pressure equalization and heat dissipation

Methodology Applied
Scientific EffectHeat dissipation: Heat Sink

Data Source

PatentEP3464946B1Linear drive with a spindle nut mounted rotatably in an end shield, and spindle
Publication Date: 2020.07.08 SEW EURODRIVE GMBH & CO KG
  • EP3464946B1 patent drawingFigure 1
  • EP3464946B1 patent drawingFigure 2
  • EP3464946B1 patent drawingFigure 3

AI summary

A linear drive with a spindle nut and a spindle, and with an end shield in which a bearing is accommodated for the rotatable mounting of the spindle nut or spindle, in particular wherein the spindle is operatively connected to the spindle nut, in particular is screwed into the spindle nut, wherein first elevations are formed on the end shield in a manner protruding in the transverse direction with respect to the axis of the spindle for connection by means of a universal joint to a device to be driven, wherein two interconnected joint parts have second elevations protruding in the transverse direction with respect to the axis of the spindle, in particular wherein an elevation is integrally formed on each of the joint parts, wherein each of the joint parts has a recess in which a first elevation is in each case inserted, in particular in each case by means of a clearance fit, in particular therefore in each case by means of a fit having a clearance, wherein the second elevations are oriented perpendicularly to the first elevations.