Filter Device Pressure Compensation Hollow Body
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Solution Overview
Problem
Existing filter devices for aqueous urea solutions in SCR exhaust systems face challenges in effectively managing pressure and volume fluctuations due to freezing, which can damage the filter material and lead to inoperability.
Innovation Solution
A filter device with an elastically resilient hollow body as a compensating element, surrounded by a compressible filling medium, acts as a pressure accumulator to manage volume increases during freezing without causing harmful pressure spikes, and is arranged downstream of the filter element to minimize housing size and maximize operational reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a cellular rubber compensating element is used upstream, then rapid pressure peaks can be smoothed out, but volume compensation during freezing is insufficient due to stiff material behavior
Solution Approach 1:
A fluid-permeable supporting body is introduced as an intermediary component between the hollow body and the filter element. This supporting body allows fluid to pass through while providing mechanical support to the hollow body, enabling both pressure smoothing and reliable volume compensation during freezing without direct contact between the compensating element and filter material
Solution Approach 2:
The hollow body is designed as a flexible membrane structure that can expand and contract to compensate for volume changes during freezing. The membrane's elasticity allows it to absorb pressure peaks while its fluid-permeable supporting body ensures proper fluid guidance and filter element protection
2Stress or pressure
If the compensating element is arranged upstream, then pressure peaks can be mitigated, but the housing size increases and filter element protection is reduced
Solution Approach 1:
The compensating element is repositioned from an upstream arrangement to a downstream arrangement behind the filter element. This dimensional repositioning allows the hollow body to be integrated into the existing housing space without increasing overall housing size, while still providing effective pressure compensation and filter element protection
3Reliability
If the hollow body is surrounded by a fluid-permeable supporting body, then operational reliability is improved, but device complexity increases
Solution Approach 1:
The fluid-permeable supporting body serves multiple functions simultaneously: it provides mechanical support to the hollow body, guides fluid flow around the compensating element, protects the filter element from direct contact with the expanding hollow body, and maintains structural integrity during freezing. This multi-functionality reduces the need for additional separate components
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
The solution provides reliable antifreeze protection and smooths out pressure peaks, ensuring the filter element's safety and extending its service life by effectively compensating for volume increases during freezing without increasing pressure, thus maintaining the filter's functionality in SCR exhaust systems.
Implementation Method 1
an at least partially fluid-permeable supporting body is arranged at least partially along the direction of greater expansion of the hollow body and along its outer contour, and that the supporting body is arranged coaxially and with a definable radial spacing of the hollow body is at least partially surrounded by the support tube
Implementation Method 2
an elastically resilient hollow body being used as the compensation element
Implementation Method 3
the flexible compensating element is designed in the form of an insert pot in the housing of the filter device and preferably consists of a cellular rubber material. With the known solution, it is also possible to compensate for the increase in volume caused by the freezing of an aqueous urea solution
Implementation Method 4
compensate for the volume increase caused by the freezing of an aqueous urea solution
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a filter device for filtering fluid, in particular in the form of an aqueous urea solution, having a filter housing (1) and a filter element (11) arranged therein, and an equalizing element for compensating pressure fluctuations or volume fluctuations in the fluid, characterized in that at least one elastically yielding hollow body (31; 41) is used as an equalizing element which has a greater spatial expansion in one direction than in another direction extending crosswise thereto, which is held in a holding part (17; 43) and which separates the fluid from a compressible filling medium, such as a working gas, by means of the wall thereof.