Eccentric Pump with Deformable Element for Urea Dosing
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Solution Overview
Problem
Pumps used for delivering liquid additives, such as urea-water solutions, in exhaust gas treatment devices face challenges like freezing at low temperatures, which can damage components, and require high dosing accuracy while being inexpensive and having a long service life, with existing designs struggling to meet these requirements, especially in the context of the SCR process.
Innovation Solution
A pump design featuring a rotationally symmetrical pump housing with an eccentric and a deformable element forming a pumping gap, where the deformable element is pressed against the housing to create a displaceable seal and closed pump volume, allowing precise liquid conveyance with centering rings for enhanced sealing and durability, and the ability to reverse direction for easy emptying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pump is designed to be in close contact with the liquid additive, then dosing accuracy is improved, but the risk of freezing damage increases
Solution Approach 1:
The patent applies beforehand cushioning by designing the pump housing with expansion compensation capability before freezing occurs. The housing is constructed to accommodate volume expansion of the liquid additive when it freezes, preventing damage to the pump components while maintaining close contact between the pump and liquid for accurate dosing.
2Object-affected harmful factors
If the delivery module is emptied when deactivated, then freezing damage is prevented, but resuming delivery becomes significantly more difficult
Solution Approach 1:
The pump housing is designed with built-in expansion compensation capacity before freezing occurs. This allows the pump to retain liquid additive during standstill periods without damage from volume expansion, eliminating the need to empty the pump before shutdown while maintaining ease of resumption.
3Object-affected harmful factors
If the pump components are designed flexibly to withstand volume expansion, then freezing protection is improved, but dosing accuracy and service life deteriorate
Solution Approach 1:
The pump housing incorporates predetermined expansion compensation capacity through its structural design, allowing it to withstand volume expansion from freezing without requiring flexible or sacrificial components. This maintains component rigidity and precision for accurate dosing while providing freezing protection.
4Measurement precision
If the pump uses a deformable element pressed against the housing, then sealing and dosing accuracy are improved, but the complexity of the pump structure increases
Solution Approach 1:
The patent employs a deformable element (flexible membrane) that is pressed against the pump housing to create sealing surfaces and define pump chambers. This flexible film approach provides effective sealing and enables precise dosing through controlled deformation, while the simplicity of using a single flexible component rather than multiple rigid parts actually reduces overall 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
The design ensures high reliability, low aging, and precise dosing accuracy, while being resistant to freezing and pressure variations, thus protecting the pump from damage and maintaining efficient operation.
Implementation Method 1
An eccentric (5) is arranged inside the pump housing (2) and rotates about a geometric axis (23) relative to the pump housing
Implementation Method 2
The deformable element (7) protrudes in the direction of the geometric axis (23) on one or both sides beyond the outer surface (6) of the eccentric (5) and has a centering ring (16) in at least one projection (20) inside
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Pump (1) for conveying a fluid, comprising at least one pump housing (2) with at least one inlet (3) and at least one outlet (4) and with a rotationally symmetric inner circumferential surface (13) and a geometric axis (23), wherein an eccentric (5) is arranged within the pump housing (2) and is rotatable relative to the pump housing (2) around the geometric axis (23), wherein a deformable element (7) is arranged in a pump gap (11) between the inner circumferential surface (13) of the pump housing (2) and an outer surface (6) of the eccentric (5), and wherein a conveying channel (8) is formed from the at least one inlet (3) to the at least one outlet (4) by the deformable element (7) and the inner circumferential surface (13) of the pump housing (2), and wherein in addition the deformable element (7) is pressed in sections against the pump housing (2) by the outer surface (6) of the eccentric (5) in such a way that at least one displaceable seal (9) of the conveying channel (8) and at least one closed pump volume (10) are formed in the conveying channel (8) and which are displaceable by a rotation of the eccentric (5) for conveying the fluid along the conveying channel (8) from the inlet (3) to the outlet (4), wherein the deformable element (7) has a protrusion (20) on one or both sides in the direction of the geometric axis (23), the protrusion extending over the outer surface (6) of the eccentric (5) which contacts the deformable element (7), and there being a centring ring (16) inside at least one protrusion (20).