Gear Housing Intermediate Chamber Sealing Under External Pressure

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Solution Overview

Problem

Existing drive devices for trench wall cutters face challenges in sealing against high external pressures and abrasive media, leading to inefficiencies and increased churning losses due to the need for large-volume pressure accumulators or pumps to equalize pressure, which are complex and bulky.

Innovation Solution

A pressure compensation system with an intermediate chamber that is pressurized and sealed from both the interior and exterior, using different types of seals to manage high internal pressures and abrasive external conditions, reducing the volume of pressure medium required and minimizing churning losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the entire interior of the gearbox housing is pressurized to equalize pressure with the ambient environment, then sealing against high external pressure is improved, but the device becomes complex and bulky due to the large volume of pressure medium required

Engineering Contradiction:
Improvesealing reliabilityVSAvoidpressure equalization system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the pressurization system into multiple independent intermediate chambers instead of pressurizing the entire gearbox interior. Each chamber is sealed by sealing elements and can be independently pressurized to a fraction of the ambient pressure. This segmentation reduces the total volume of pressure medium required while maintaining effective sealing against high external pressures.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces intermediate chambers as intermediary spaces between the gearbox interior and the ambient environment. These chambers act as buffer zones that reduce the pressure differential that sealing elements must withstand. By pressurizing these intermediate chambers rather than the entire gearbox interior, the system achieves effective sealing with reduced complexity and smaller pressure medium volume.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If compressed air or gas is used to pressurize the gearbox interior, then pressure equalization is achieved, but large quantities of compressed air or gas are required which must be stored in balloons or pressure vessels

Engineering Contradiction:
Improvepressure equalizationVSAvoidpressure medium storage volume
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent segments the pressurization volume into multiple small intermediate chambers instead of requiring a single large-volume pressure storage system. Each chamber requires only a small amount of compressed air or gas to achieve the necessary pressure differential, eliminating the need for large balloons or pressure vessels.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies pressure equalization locally in each intermediate chamber rather than globally throughout the entire gearbox interior. Each chamber is pressurized to a level sufficient for its specific sealing requirements, optimizing the use of compressed air or gas and minimizing the total volume of pressure medium needed.

Inventive Principle:
Principle #3Local quality

3Quantity of substance

If the gearbox housing is filled almost completely with lubricating oil to minimize air space volume, then pressure medium volume is reduced, but churning losses increase significantly

Engineering Contradiction:
Improvepressure medium volumeVSAvoidchurning losses
Core Design Contradiction:
Quantity of substanceVSLoss of energy

Solution Approach 1:

The patent creates segmented intermediate chambers that require minimal pressure medium volume while maintaining effective pressure equalization. This segmentation allows the gearbox interior to remain partially filled with lubricating oil without the excessive churning losses that would occur with complete filling, as the small intermediate chambers require only small volumes of compressed air or gas.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies partial pressurization to the intermediate chambers rather than fully pressurizing the entire gearbox interior. This partial action achieves sufficient pressure equalization for sealing purposes while minimizing the volume of pressure medium required and avoiding the energy losses associated with churning large volumes of lubricating oil.

Inventive Principle:
Principle #16Partial or excessive 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 solution provides reliable sealing at high pressure differences without the need for large-volume pressure accumulators, maintaining efficiency and reducing temperature issues, while allowing for independent pressurization and monitoring of intermediate chambers to ensure effective pressure equalization.

Implementation Method 1

a pressure equalization device which comprises at least one intermediate chamber (20) which can be pressurized by a pressure source (24) and is sealed from the interior (16) by an inner seal (21) and from the environment by an outer seal (22)

Methodology Applied
Scientific EffectPressure equalization: Pressure Gradient

Data Source

PatentEP4194612B1Drive and/or gear housing for driving a trench wall cutter
Publication Date: 2024.11.20 LIEBHERR COMPONENTS BIBERACH GMBH
  • EP4194612B1 patent drawingFigure 1
  • EP4194612B1 patent drawingFigure 2~3
  • EP4194612B1 patent drawingFigure 4~5

AI summary

The present invention relates to a drive and/or gearbox housing for the drive (4) of a diaphragm wall cutter (1), which encloses an interior space (16) for receiving drive and/or gearbox elements and comprises two housing parts (13, 14) that are rotatable relative to each other and are sealed from each other by a sealing device (15). The invention further relates to the drive device and a diaphragm wall cutter with such a drive device. It is proposed not to pressurize the entire interior space of the housing, but only an intermediate space facing the environment, and to seal this space on one side against the interior and on the other against the environment.According to the invention, the drive and/or transmission housing comprises at least one intermediate chamber (20) for pressure equalization between the interior (16) and the environment, which is sealed to the interior by an inner seal (21) and to the environment (27) by an outer seal (22). Such a sealed intermediate chamber (20) between the housing interior and the environment, which can be significantly smaller in volume than the interior, makes pressurization for pressure equalization between the interior and the environment considerably easier.