Radiator Fan Module Hub Overlap to Reduce Swirling Gap Flow
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Solution Overview
Problem
The efficiency of radiator fan systems in motor vehicles is reduced by unfavorable swirling gap flows in the region of the hub of the fan impeller and motor support, particularly when the motor support is positioned upstream of the fan impeller, leading to adverse interactions with the main airflow.
Innovation Solution
The radiator fan module features a fan shroud with a fan impeller aperture containing a motor support with struts connected to the shroud and a fan impeller with radially outward blades, where the housing parts have different diameters, forming an axial gap that minimizes adverse flow influences by creating a radial overlap, and the radiator fan blades are sickle-shaped with undulating edges to enhance airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the motor support is positioned upstream of the fan impeller, then the motor support structure is simplified and easier to manufacture, but adverse swirling gap flows are generated that reduce fan efficiency
Solution Approach 1:
A gap flow control element is introduced as an intermediary component between the motor support and fan impeller. This element actively manages the gap flow, converting the harmful swirling flow into a more favorable flow pattern that reduces adverse interactions while maintaining the simplified upstream motor support positioning.
Solution Approach 2:
The gap flow control element modifies the flow parameters (velocity distribution, flow direction, turbulence intensity) in the gap region between motor support and fan impeller. By changing these parameters, the harmful swirling flow is transformed into a more uniform flow that enhances rather than reduces fan efficiency.
2Productivity
If the gap between the fan impeller and the edge of the opening in the fan shroud is minimized, then fan efficiency is improved, but the risk of contact and mechanical failure increases
Solution Approach 1:
The fan impeller is designed with radial play (axial mobility) that allows dynamic adjustment of the impeller position relative to the fan shroud opening. This dynamic capability enables the system to maintain optimal small gaps for efficiency while automatically compensating for manufacturing tolerances and thermal expansions to prevent contact and ensure reliability.
3Productivity
If the housing parts have different diameters forming a radial overlap, then adverse flow influences are reduced, but the device complexity increases
Solution Approach 1:
The housing parts (motor support and fan impeller housing) are designed with different diameters creating an asymmetric radial overlap configuration. This asymmetric design deliberately generates a controlled radial component in the gap flow that counteracts adverse swirling flows, improving overall airflow efficiency despite the increased structural complexity.
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 effectively reduces adverse flow influences, resulting in improved cooling efficiency and system performance by optimizing airflow through the radiator core, even at varying vehicle speeds.
Implementation Method 1
The pressure difference between the region in front of the radiator core and the region behind the shroud body is thus relatively large. Thus, when the vehicle is at a standstill, the fan draws a relatively large quantity of air through the radiator core of the radiator.
Implementation Method 2
A cooling device in the form of a fluid-type cooling circuit is commonly interposed, with a heat exchanger (radiator) being exposed to the flow of relative wind and to the air flow from the fan device.
Data Source
AI summary
A radiator fan module for a motor vehicle has a fan shroud with a fan impeller aperture and a motor support disposed within the fan impeller aperture, for an electric motor, and has a support-side housing part and has a plurality of struts that are connected to the fan shroud. A fan impeller is disposed in the fan impeller aperture and is driven in rotation about an axis of rotation. The fan impeller has a hub-side housing part and a plurality of radially outwardly directed radiator fan blades disposed on the hub-side housing part. The support-side housing part and the hub-side housing part have different diameters, wherein the support-side housing part or the hub-side housing part that has a greater diameter overlaps the other of the support-side housing part or the hub-side housing part, with an air gap being formed.