Lubricating Unit for Screw-Nut Drive with Post-Assembly Oil Filling

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Solution Overview

Problem

The existing lubricating units for screw drives face challenges in achieving a reliable and liquid-tight connection between the cover and base body, especially when filled with lubricating oil, as material-to-material connections like welding or gluing are not effective due to the risk of oil leakage, and the slow absorption of oil by the foam storage disk makes the filling process time-consuming and inefficient.

Innovation Solution

The lubricating unit incorporates oil filling openings in the housing, allowing for lubricating oil to be filled after the cover is connected to the base body, which prevents oil film interference during joining and enables quick absorption by the storage disk, with T-shaped oil filling recesses and a bent extension for efficient oil distribution, along with anti-twist mechanisms to secure the fastening components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If material-to-material connection methods (welding or gluing) are used to connect the cover to the base body, then the connection can be cost-effective and liquid-tight, but the connection point may be wetted with lubricating oil which prevents reliable material connection

Engineering Contradiction:
Improveconnection reliabilityVSAvoidoil film interference
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by providing oil filling openings that allow the housing to be filled with lubricating oil AFTER the cover is materially connected to the base body. This reverses the traditional sequence where oil would be present during joining, thereby preventing oil film interference at the connection point while still achieving reliable liquid-tight connection through welding or gluing

Inventive Principle:
Principle #10Preliminary action

2Duration of action of moving object

If the storage disk absorbs lubricating oil slowly due to optimized pore structure, then the lubricating oil is released comparatively slowly during operation, but the filling process takes a long time

Engineering Contradiction:
Improveoil release durationVSAvoidfilling time
Core Design Contradiction:
Duration of action of moving objectVSLoss of time

Solution Approach 1:

The patent applies local quality by providing T-shaped oil filling recesses in the storage disk. The vertical portion of the T-shape provides a direct pathway for rapid oil filling from the opening, while the horizontal portion allows the optimized pore structure foam to slowly absorb and release oil during operation. This local structural differentiation enables both rapid filling and controlled long-term oil release

Inventive Principle:
Principle #3Local quality

3Quantity of substance

If the housing is filled with lubricating oil before connecting the cover to the base body, then the storage disk can be saturated with oil, but the connection point will be wetted with oil preventing material connection

Engineering Contradiction:
Improvelubricating oil quantityVSAvoidconnection reliability
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent reverses the traditional sequence by performing the material connection of the cover to the base body FIRST, and then filling the housing with lubricating oil through the provided oil filling openings. This ensures the connection point remains dry during joining for reliable material connection, while still allowing complete saturation of the storage disk with lubricating oil afterward

Inventive Principle:
Principle #10Preliminary action

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 ensures a reliable and liquid-tight connection between the cover and base body, allows for efficient oil filling and absorption, and provides a secure fastening mechanism, enhancing the operational stability and manufacturing efficiency of the lubricating unit.

Implementation Method 1

The storage plate is made of an open-cell foam so that it can absorb and store lubricating oil

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 2

the foam absorbs the lubricating oil until it is saturated with lubricating oil

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 3

the body and the lid are injection molded from plastic

Methodology Applied
Scientific EffectInjection molding: 3D Printing

Implementation Method 4

the front oil filling openings in the cover can be closed with a longitudinal seal that is required anyway, so that no lubricating oil can escape through the oil filling opening

Methodology Applied
Scientific EffectSealing:

Data Source

PatentEP2322824B1Lubricating unit for a screw-nut drive
Publication Date: 2011.12.28 ROBERT BOSCH GMBH
  • EP2322824B1 patent drawingFigure 1
  • EP2322824B1 patent drawingFigure 2~3
  • EP2322824B1 patent drawingFigure 4

AI summary

The invention relates to a lubrication unit (20) for use with a threaded drive (10), consisting of a spindle (12) extending in a longitudinal direction (11) and a nut (14) surrounding the spindle (12), wherein the lubrication unit (20) comprises a hollow cylindrical housing (30) which has a base body (31) with an annular cavity (32) which is closed at its end face by a separate cover (36), wherein a storage plate (70) made of foam, which is bent into a ring, is received in the cavity (32), wherein the storage plate (70) is penetrated by at least one oil filling recess (79), wherein fastening means (23) are provided on the longitudinal end face of the housing (30) opposite the cover (36), with which the housing (30) can be fastened to the nut (14).According to the invention, the lid (36) is materially connected to the base body (31), wherein at least one oil filling opening (37) is provided in the housing (30), which is open towards the oil filling recess (79).