Radial Fan Differential Pressure Measurement via Axial Strut

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Solution Overview

Problem

Centrifugal fans lack an efficient and cost-effective method for measuring volume flow at constant fan wheel speed, with existing solutions experiencing poor measuring accuracy due to complex and expensive assembly of pressure measurement systems, especially for small volume flows.

Innovation Solution

Integration of a differential pressure sensor within the axial strut of a centrifugal fan, which directly measures pressure differences between the suction and pressure sides, eliminating the need for ring lines and pressure hoses, and utilizing a hot-film sensor to calculate volume flow with improved accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a ring line and hose line assembly is used for pressure measurement, then pressure measurement capability is achieved, but device complexity and cost increase

Engineering Contradiction:
Improvepressure measurement capabilityVSAvoidassembly complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the pressure measurement function directly into the axial strut structure by integrating a differential pressure sensor within a hollow channel that extends from the suction side to the pressure side. This eliminates the need for separate ring lines and hose lines, reducing device complexity while maintaining pressure measurement capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The axial strut serves multiple functions: it provides structural support for the fan wheel and simultaneously houses the differential pressure sensor for volume flow measurement. This multi-functionality reduces the number of separate components needed, simplifying the overall device structure.

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

2Productivity

If conventional pressure measurement systems are used, then volume flow determination is possible, but measuring accuracy deteriorates for small volume flows

Engineering Contradiction:
Improvevolume flow determination capabilityVSAvoidmeasuring accuracy at small volume flows
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent uses a differential pressure sensor as an intermediary measurement device that directly measures the pressure difference between the suction and pressure sides. This intermediary approach provides a linear relationship with volume flow, improving measurement accuracy especially at small volume flows where conventional methods fail.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If differential pressure sensor is placed in hollow channel of axial strut, then measurement accuracy improves, but device complexity increases

Engineering Contradiction:
Improvedifferential pressure measurement accuracyVSAvoidaxial strut structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The differential pressure sensor is merged with the axial strut structure by placing it within a hollow channel that is an integral part of the strut. This integration approach improves measurement accuracy while avoiding the need for additional external components, thus not increasing overall device complexity.

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

This solution provides a cost-effective and accurate method for determining volume flow, even at low flow rates, without affecting the fan's efficiency or noise performance, and can be scaled for various fan sizes.

Implementation Method 1

at least one differential pressure sensor is arranged in the hollow channel, which directly detects or measures a pressure difference of the respective static air pressure on the suction side and the pressure side

Methodology Applied
Scientific EffectDifferential pressure measurement: Pressure Gradient

Implementation Method 2

the differential pressure sensor is designed as a hot-film sensor. Due to the pressure difference on the suction side and the pressure side during operation of the centrifugal fan, air flows through the hollow channel of the axial strut and consequently over the hot-film sensor. The air flow influences the temperature at the hot-film sensor depending on the pressure difference

Methodology Applied
Scientific EffectHot-film sensor effect: Thermocouple

Data Source

PatentEP3622181B1Radial ventilator with differential pressure measurement
Publication Date: 2020.08.05 EBM PAPST MULFINGEN GMBH & CO KG
  • EP3622181B1 patent drawingFigure 1~2
  • EP3622181B1 patent drawingFigure 3~4
  • EP3622181B1 patent drawing

AI summary

The invention relates to a radial ventilator (1) comprising a ventilator wheel (2), a motor which drives the ventilator wheel, and a ventilator housing (3). The radial ventilator (1) has a suction side (S), which is on the suction side when viewed in the flow direction, and a pressure side (D), which lies axially opposite the suction side. The ventilator housing (3) is made of a suction-side front part (4) and a pressure-side rear part (5), between which the ventilator wheel (3) is arranged when viewed in the axial direction. The front part (4) and the rear part (5) are connected by at least one axial brace (6) that has a hollow channel (7) which is open towards the suction side (S) and the pressure side (D) and in which at least one differential pressure sensor (8) is arranged, said differential pressure sensor directly detecting a pressure difference of the respective static air pressure on the suction side (S) and the pressure side (D) of the radial ventilator (1) during the operation of the radial ventilator (1).