Orbital Pump Stiffening Ring Thermal Expansion
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Solution Overview
Problem
Pumps used for delivering liquid exhaust-gas purification additives, such as urea-water solutions, face challenges including freezing at low temperatures, which can damage components, and maintaining dosing accuracy despite temperature and pressure variations.
Innovation Solution
A pump design featuring a deformable element within a pump housing with a stiffening ring, where the deformable element forms a delivery duct and is pressed against the housing to create displaceable seals, allowing for precise liquid delivery while compensating for thermal expansion through carefully managed coefficients of thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump is made flexible to protect against freezing damage, then resistance to freezing is improved, but dosing accuracy deteriorates
Solution Approach 1:
The pump housing has different rigidity characteristics in different regions: the first region (opposite the delivery duct) is designed to be more rigid to maintain dosing accuracy, while the second region is more flexible to accommodate freezing expansion. This local differentiation allows the pump to simultaneously achieve both freezing resistance and dosing precision.
Solution Approach 2:
The pump housing is constructed as a composite structure with regions of different stiffness, combining rigid and flexible characteristics in a single component. This composite design enables the housing to provide both the structural stability needed for accurate dosing and the flexibility needed to withstand freezing conditions.
2Reliability
If the pump is evacuated to prevent freezing damage, then resistance to freezing is improved, but productivity deteriorates
Solution Approach 1:
The pump housing is pre-designed with specific rigidity characteristics before operation, with the first region configured to maintain dosing accuracy and the second region configured to accommodate freezing expansion. This preliminary structural configuration eliminates the need for evacuation procedures, allowing the pump to maintain both freezing resistance and full productivity during operation.
3Manufacturing precision
If the pump housing is made rigid to maintain dosing accuracy, then manufacturing precision is improved, but resistance to freezing deteriorates
Solution Approach 1:
The pump housing has different rigidity characteristics in different regions: the first region (opposite the delivery duct) is designed to be more rigid to maintain dosing accuracy, while the second region is more flexible to accommodate freezing expansion. This local differentiation allows the pump to simultaneously achieve both freezing resistance and dosing precision.
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 pump design enhances durability, dosing accuracy, and resistance to freezing, ensuring reliable and precise delivery of liquid additives across varying temperatures, reducing the risk of component damage and improving operational efficiency.
Implementation Method 1
a first coefficient of thermal expansion of the stiffening ring is lower than a third coefficient of thermal expansion of the pump housing
Data Source
AI summary
A pump for delivering a fluid includes: a pump housing having an inlet and an outlet, and having an inner circumferential face; a drive shaft; an eccentric inside the pump housing, the eccentric being eccentrically movable relative to the pump housing; a deformable element arranged in a pump gap between the inner circumferential face and an outer surface of the eccentric, the deformable element and the inner circumferential face defining a delivery channel. The deformable element is forced against the pump housing by the outer surface of the eccentric along at least a portion of the delivery channel such to form a sliding sealing of the delivery channel that can be slid along the delivery channel from the inlet to the outlet to deliver fluid by movement of the eccentric. A reinforcing ring has a coefficient of thermal expansion smaller than a coefficient of thermal expansion of the pump housing.