Pump Assembly Sealing and Cooling for SCR Systems
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Solution Overview
Problem
Existing pump assemblies for selective catalytic reduction systems face challenges such as urea precipitation at high temperatures, leading to blockages and inefficient NOx emission reduction, and solenoid coil performance degradation, along with packaging and heat management issues due to the size and arrangement of the solenoid coil.
Innovation Solution
A pump assembly design featuring a pump sub-assembly with grooves for seal members to simplify assembly and reduce housing complexity, incorporating a plastic over-moulding member for the solenoid coil and actuator components, and a method of manufacturing that includes deep drawing and injection moulding to reduce material waste and optimize cooling, while providing fluid-tight seals and efficient reagent flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a water cooling system is provided around the solenoid actuator, then the solenoid coil performance is maintained at high temperatures, but the packaging size and mass of the pump assembly increase
Solution Approach 1:
The patent combines the cooling function with the existing pump housing structure by integrating cooling channels directly into the housing that receives the pump sub-assembly. This merges the cooling system with the structural housing, eliminating the need for separate cooling components and reducing overall mass while maintaining solenoid coil performance.
2Reliability
If the solenoid coil size is increased to improve performance, then the solenoid actuator reliability improves, but the packaging size of the pump assembly increases
Solution Approach 1:
The patent nests the solenoid coil within the pump sub-assembly structure, specifically positioning it within the housing cavity. This nested arrangement allows the solenoid coil to be integrated into the existing spatial envelope of the pump assembly without requiring additional external space, thereby maintaining actuator reliability while avoiding increased packaging area.
3Ease of manufacture
If seal members are provided in grooves in the pump sub-assembly outer face, then assembly is simplified and housing complexity is reduced, but manufacturing precision requirements for the grooves increase
Solution Approach 1:
The patent employs elastomeric seal members that can deform to accommodate minor variations in groove dimensions. This flexibility compensates for typical manufacturing tolerances in groove fabrication, allowing assembly to be simplified through the use of grooves while maintaining fluid-tight sealing without requiring excessively tight dimensional controls on the grooves themselves.
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 enhances assembly efficiency, reduces packaging size and mass, and improves heat management, ensuring robust operation and effective NOx emission reduction by preventing urea precipitation and maintaining solenoid coil performance at high temperatures.
Implementation Method 1
The pumping work conducted by the dosing arrangement of such solenoid actuated pumps is created by a solenoid coil acting on the magnetic armature of a plunger armature assembly.
Implementation Method 2
Many known pump assembly arrangements therefore include a water cooling system, e.g. by means of the provision of a water jacket around the solenoid actuator and the provision of water input and output ports to the jacket in order to provide a flow of cooling water.
Implementation Method 3
At least one seal member is provided to seal the pump sub-assembly within the housing sub-assembly, the seal member being provided in a groove in an outer face of the pump sub-assembly, the seal member providing a fluid tight seal
Data Source
Figure 1
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AI summary
A pump assembly (100) for use in a selective catalytic reduction system, the pump assembly comprising: a pump sub-assembly (12) defining a pump axis (A); and a housing sub-assembly (30) including a cavity (120) for receiving the pump sub-assembly and comprising an inlet port (52) for receiving a reagent for supply to the pump sub-assembly via a flow path(130, 132, 142); wherein at least one seal member (124, 126, 38) is provided to seal the pump sub-assembly within the housing sub-assembly, the seal member being provided in a groove (140) in an outer face of the pump sub-assembly, the seal member providing a fluid tight seal.