Side Channel Compressor Bearing Preload for Fuel Cell Hydrogen Delivery

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Solution Overview

Problem

Side channel compressors for fuel cell systems face inefficiencies due to imprecise guidance of the compressor wheel, leading to increased gap sizes between components, reduced encapsulation, and potential damage from lateral forces, which results in reduced hydrogen delivery and compression efficiency.

Innovation Solution

The compressor design incorporates an upper and lower housing part with a cylindrical extension and a spacer to adjust bearing preload force, allowing for precise guidance and reduced gap sizes between the compressor wheel and housing, enhancing encapsulation and efficiency by dissipating lateral forces effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the distance between contact surfaces is increased to prevent collision, then reliability is improved, but manufacturing precision deteriorates due to larger gaps

Engineering Contradiction:
Improveprevention of compressor wheel collisionVSAvoidgap size between components
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-loading the bearings with a predetermined force before operation. The housing exerts a bearing preload force on the first and/or second bearing, which is calculated in advance to compensate for lateral forces during operation. This pre-positioning ensures the compressor wheel maintains optimal gap distance without collision risk, resolving the contradiction between reliability and precision.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If bearing diameter is increased to improve guidance precision, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:
Improveguidance precision of compressor wheelVSAvoidbearing arrangement complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by differentiating the bearing diameters - the first bearing has a different diameter than the second bearing. This localized variation optimizes guidance precision at specific critical points without requiring all bearings to be large diameter. The first bearing (with larger diameter) provides primary support, while the second bearing (with smaller diameter) provides auxiliary guidance, achieving high precision without uniform complexity throughout the system.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3794236B1Side channel compressor for a fuel cell system for conveying and/or compressing a gaseous medium
Publication Date: 2023.07.26 ROBERT BOSCH GMBH
  • EP3794236B1 patent drawingFigure 1
  • EP3794236B1 patent drawingFigure 2
  • EP3794236B1 patent drawingFigure 3~4

AI summary

The invention relates to a side channel compressor (1) for a fuel cell system (37) for conveying and/or compressing a gaseous medium, in particular hydrogen, comprising a housing (3), a compressor chamber (30) which is located in the housing (3) and has at least one circumferential side channel (19, 21), a compressor impeller (2) which is located in the housing (3) and is arranged on a drive shaft (9) that is rotatable about an axis of rotation (4), wherein the compressor impeller (2) has conveying cells (28) arranged at its circumference in the region of the compressor chamber (30), and comprising in each case one gas inlet opening (14) formed on the housing (3) and one gas outlet opening (16), which openings are fluidically connected to one another via the compressor chamber (30), in particular the two side channels (19, 21), wherein the housing (3) has a first and a second run-on surface (23, 25) which in each case face the compressor impeller (2) and extend axially relative to the axis of rotation (4), and wherein an inner and an outer axial gap are in each case formed in these regions between the housing (3) and the compressor impeller (2). According to the invention, the rotatable components of the side channel compressor (1) are supported by means of a first bearing (18) and a second bearing (22), wherein the first bearing (18) is located between the drive shaft (9) and the housing (3) and the second bearing (22) is located between the compressor impeller (2) and the housing (3).