Spindle Motor Self-Lubricating Pump and Oil Bath

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Solution Overview

Problem

Spindle motors have a limited service life due to insufficient lubrication, requiring frequent relubrication and resulting in short operational intervals and potential oil contamination.

Innovation Solution

Integration of a lubricant pump within the threaded spindle, which creates an oil bath for continuous lubrication, utilizing high-pressure seals to maintain oil containment and ensure lubrication regardless of installation position, and a compact design with efficient heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If a limited volume of grease is used for lubrication, then the device structure remains simple, but the service life becomes short and frequent relubrication is required

Engineering Contradiction:
Improveservice lifeVSAvoidlubrication system complexity
Core Design Contradiction:
Duration of action of moving objectVSDevice complexity

Solution Approach 1:

The spindle motor performs self-lubrication by utilizing its own operational movements to pump oil from the oil bath to the lubrication points. The reciprocating motion of the piston rod and rotation of the threaded spindle automatically drive the oil circulation without external intervention, enabling continuous operation without manual relubrication

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

A hydraulic oil pump is integrated into the threaded spindle to create a closed-loop oil circulation system. The pump draws oil from the oil bath and delivers it to lubrication points, while high-pressure seals maintain oil containment, transforming the lubrication system from simple grease application to an active hydraulic lubrication circuit that extends service life

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Loss of energy

If local lubrication points are used, then the structure remains compact, but friction losses increase and heat dissipation becomes insufficient

Engineering Contradiction:
Improvefriction lossesVSAvoidheat dissipation
Core Design Contradiction:
Loss of energyVSTemperature

Solution Approach 1:

The oil bath serves multiple functions simultaneously: it acts as a lubricant reservoir, a cooling medium for heat dissipation, and a seal lubrication source. The same oil circulation system lubricates both the threaded spindle and seal surfaces, reducing friction losses across multiple contact points while the extensive oil-bathed surfaces provide efficient heat dissipation

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system transitions from dry or grease-lubricated surfaces to oil-lubricated surfaces with continuous circulation. This parameter change in lubrication medium and delivery method significantly reduces friction coefficients at bearing and seal interfaces, while the oil's thermal capacity and circulation enable effective heat removal from friction zones

Inventive Principle:
Principle #35Parameter changes

3Reliability

If high-pressure seals are used to contain oil, then continuous lubrication is achieved, but the sealing system becomes more complex

Engineering Contradiction:
Improvecontinuous lubricationVSAvoidsealing system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sealing function is merged with the existing structural components of the spindle motor. High-pressure seals are integrated into the piston rod assembly and threaded spindle structure, combining seal containment with mechanical support functions. This reduces the number of separate sealing components while maintaining reliable oil containment for continuous lubrication

Inventive Principle:
Principle #5Merging (Combining)

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 continuous operation without lubrication interruptions, extends service life, reduces friction losses, and improves heat dissipation, while maintaining motor functionality and preventing oil contamination.

Implementation Method 1

a lubricant pump being integrated into the threaded spindle in such a way that the threaded spindle also works together with other components as a lubricant pump

Methodology Applied
Scientific EffectPumping: Pump

Implementation Method 2

Heat dissipation is also improved, since the heat generated inside is spread out better and the entire surface can therefore be used to dissipate heat from locally limited sources of friction and thus heat sources

Methodology Applied
Scientific EffectHeat dissipation: Heat Sink

Implementation Method 3

the spindle area is correspondingly sealed against the spatial area of the electric motor and against the environment with seals that are able to seal off an overpressure of more than 2 bar

Methodology Applied
Scientific EffectPressure sealing: Pressure Gradient

Data Source

PatentEP2180974B1Spindle motor
Publication Date: 2011.11.23 SEW EURODRIVE GMBH & CO KG
  • EP2180974B1 patent drawingFigure 1
  • EP2180974B1 patent drawingFigure 1a
  • EP2180974B1 patent drawingFigure 2

AI summary

The invention relates to a spindle motor, comprising an electric motor having a rotor connected to a threaded spindle, the thread of which is engaged with a thread of a spindle nut connected to a piston rod, wherein the spindle nut, along with the piston rod, is axially guided in a housing part, wherein a guide part is connected to the spindle nut and piston rod for axially guiding the same, wherein a lubricant pump is integrated into the threaded spindle.