Housing Sealing Surface for Drive Device Pressure Testing

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Solution Overview

Problem

Existing housings for drive devices in motor vehicles, such as windshield wiper drives, lack a method to effectively test the tightness of pressure equalization membranes, which are crucial for preventing pressure fluctuations and liquid ingress, due to uneven geometries and fissures that hinder the assessment of membrane functionality and connection integrity.

Innovation Solution

A housing design featuring a continuous circumferential sealing surface surrounding the pressure equalization membrane, allowing for a leak test by applying compressed air or liquid, combined with reinforcing ribs that prevent liquid accumulation, enabling direct assessment of membrane functionality and connection tightness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pressure equalization membrane is installed on a housing with uneven geometry and fissures, then the membrane can provide pressure equalization and liquid prevention, but the tightness of the connection between the membrane and housing cannot be tested

Engineering Contradiction:
Improvetightness of connectionVSAvoidtestability of membrane functionality
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The invention separates the sealing function from the testing function by introducing a distinct sealing surface that is geometrically defined and accessible. The sealing surface is created as a separate feature on the housing that allows testing equipment to access and seal against the pressure equalization membrane independently from the complex housing geometry.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention introduces a sealing surface as an intermediary element between the housing and the testing equipment. This sealing surface acts as a mediator that enables the application of testing devices to the pressure equalization membrane, allowing tightness testing without direct access to the membrane itself through the complex housing geometry.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If the housing geometry surrounding the pressure equalization membrane is uneven with fissures, then the membrane can be installed, but pre-assembly tightness checks become necessary and time-consuming

Engineering Contradiction:
Improveassembly processVSAvoidtime for pre-assembly checks
Core Design Contradiction:
Ease of manufactureVSLoss of time

Solution Approach 1:

The sealing surface is designed into the housing structure during manufacturing, preparing the housing in advance for tightness testing. This preliminary preparation of the sealing surface allows for quick and easy testing without requiring complex pre-assembly procedures or additional preparation steps.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If a sealing surface is introduced to enable testing, then tightness can be assessed, but the housing geometry becomes more complex

Engineering Contradiction:
Improvetestability of connection tightnessVSAvoidhousing geometry
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sealing surface is introduced as a localized feature with specific geometric properties (flat, accessible surface) that is distinct from the rest of the complex housing geometry. This localized approach allows the sealing surface to provide testing functionality without requiring the entire housing to be redesigned, maintaining simplicity where possible while adding complexity only where necessary for testing.

Inventive Principle:
Principle #3Local quality

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 reliable testing of pressure equalization membrane tightness and connection integrity, ensuring the membrane's impermeability and air exchange function, thereby preventing critical pressure fluctuations and liquid ingress, and reducing the need for pre-assembly checks.

Implementation Method 1

The task of pressure-equalizing membranes is to enable pressure equalization between the interior volume of a housing and the environment, in order to avoid critical positive and/or negative pressures due to temperature fluctuations.

Methodology Applied
Scientific EffectPressure equalization: Pressure Gradient

Implementation Method 2

Pressure compensation membranes have the function of preventing liquid from entering the interior of the housing.

Methodology Applied
Scientific EffectLiquid impermeability: Hydrophobe

Implementation Method 3

applying compressed air or a liquid such as water to the pressure compensation membrane from the outside. The functionality or damage of the pressure equalization membrane and the weld seam can be checked on the basis of the volume flow to be measured or the pressure applied.

Methodology Applied
Scientific EffectCompressed air application: Pressure Increase

Data Source

PatentEP2274817B1Housing for a drive device and drive device
Publication Date: 2013.03.06 ROBERT BOSCH GMBH
  • EP2274817B1 patent drawingFigure 1~2
  • EP2274817B1 patent drawingFigure 3~5

AI summary

The invention relates to a housing (2) for a drive device, especially for an adjusting device and/or a windshield wiper drive in a motor vehicle, comprising a pressure compensating membrane (4) obturating a housing opening (7). The invention is characterized in that the pressure compensating membrane (4) has a peripheral sealing surface (11) which extends continuously in the direction of circumference. The invention further relates to a drive device and to a method for testing the operativeness of a pressure compensating membrane (4).