Self-priming DEF Pump with Corrosion-Resistant Materials
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Solution Overview
Problem
Conventional diesel exhaust fluid (DEF) pumps face issues such as corrosion from DEF, urea crystallization leading to increased torque requirements and self-priming challenges, and the need for extensive disassembly for maintenance. Additionally, these pumps can be damaged by running dry or with insufficient fluid, and there is a desire for improved communication with engines and reduced electromagnetic interference (EMI).
Innovation Solution
The development of a self-priming diesel exhaust fluid (DEF) gear pump that uses 316 stainless steel and carbon-filled PEEK components to resist corrosion and urea crystallization. The pump is designed to operate effectively even when dry or with minimal fluid, featuring a pressure sensor to prevent damage from dry-running and a CAN bus interface for communication with engine control modules. The design also includes features to minimize EMI and simplify manufacturing by eliminating the need for extensive shimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metals are used for bearing surfaces, then the pump structure is simple and cost-effective, but DEF causes corrosion of the bearing surfaces
Solution Approach 1:
The patent applies composite materials by combining 316 stainless steel for the bearing surfaces with carbon-filled PEEK plastic for the gears. This composite approach provides superior corrosion resistance to DEF while maintaining structural integrity and manufacturability. The stainless steel bearing surfaces resist DEF corrosion, while the carbon-filled PEEK gears provide adequate strength and wear resistance without corroding.
2Productivity
If the pump operates after DEF dries and crystallizes between bearing surfaces, then the pump can continue operating, but the torque required to spin the gears increases greatly
Solution Approach 1:
The patent implements a preliminary action by incorporating a purge mode that activates before crystallization becomes problematic. The controller detects when DEF levels are low or the pump has been idle, and automatically initiates a purge sequence that introduces fresh DEF to prevent crystallization. This preliminary intervention prevents the high-torque crystallization condition from developing in the first place.
Solution Approach 2:
The patent uses feedback control through a controller that monitors pump operation status, DEF levels, and motor current. When the controller detects conditions predisposing to crystallization (idle operation, low DEF levels, or elevated current), it activates the purge mode to introduce fresh DEF. This feedback mechanism continuously prevents crystallization buildup, maintaining normal torque levels.
3Ease of operation
If the pump is designed to be self-priming, then the pump can restart after shutdown, but the pump may not be strong enough to break free of crystallized DEF
Solution Approach 1:
The patent applies preliminary action by implementing a purge mode that activates before self-priming is attempted. When the pump shuts down and restarts, the controller first initiates a purge sequence that introduces fresh DEF to dissolve any crystallized urea from the bearing surfaces. This preliminary dissolution action ensures that when self-priming subsequently occurs, the gears encounter minimal resistance and can break free easily without requiring excessive force.
4Object-generated harmful factors
If compressed air is used to purge the DEF supply system, then the system is cleaned, but urea crystallization occurs between bearing surfaces
Solution Approach 1:
The patent applies the extraction principle by removing the harmful compressed air purge step from the system. Instead of using compressed air that causes urea crystallization, the system uses a dedicated purge mode that introduces fresh DEF through the pump. This extraction of the problematic compressed air step eliminates the crystallization issue while maintaining system cleaning functionality through DEF circulation.
Solution Approach 2:
The patent uses fresh DEF as an intermediary substance to replace compressed air for the purge function. Rather than directly introducing compressed air that causes crystallization, the system introduces fresh DEF as a mediating fluid that both cleans the system and prevents crystallization. The fresh DEF acts as an intermediary that achieves the cleaning objective without the harmful side effects of compressed air.
5Productivity
If the pump runs dry or with insufficient fluid, then the pump continues operating, but the pump can be destroyed
Solution Approach 1:
The patent implements feedback control through a controller that continuously monitors pump operation status, motor current, and pressure differential. When the controller detects dry-running conditions (abnormally high current, excessive pressure differential, or low DEF level sensors), it immediately shuts down the pump motor to prevent damage. This feedback mechanism continuously monitors operating conditions and takes protective action before destruction can occur.
Solution Approach 2:
The patent applies preliminary action by implementing predictive monitoring that detects early signs of dry-running conditions before catastrophic damage occurs. The controller monitors motor current, pressure differential, and DEF level sensors to identify developing dry-running situations. When early warning signs are detected, the system initiates a controlled shutdown sequence that prevents damage while minimizing operational interruption.
6Manufacturing precision
If extensive shimming is required for manufacturing, then precise alignment is achieved, but the manufacturing process becomes complex and time-consuming
Solution Approach 1:
The patent applies equipotentiality by designing the pump with self-aligning bearing surfaces and gear interfaces that inherently maintain proper alignment without requiring external adjustment. The bearing housings and gear mounts are precision-cast with built-in alignment features that create an equipotential alignment condition throughout the assembly. This eliminates the need for shimming while maintaining manufacturing precision through design-inherent alignment.
Solution Approach 2:
The patent uses segmentation by dividing the pump into modular components with standardized interfaces. The bearing housings, gear carriers, and end caps are designed as separate modules with precision-machined mating surfaces that self-align during assembly. This segmentation allows each module to be manufactured and aligned independently, then assembled without requiring extensive shimming, thereby reducing manufacturing complexity while maintaining 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 self-priming DEF pump effectively addresses the challenges of corrosion, urea crystallization, and dry-running, ensuring reliable operation across varying conditions. Its ability to communicate with engine control modules enhances operational flexibility, and the materials and design choices reduce the risk of damage and improve manufacturing efficiency.
Implementation Method 1
DEF will corrode most metals that are typically used for bearing surfaces or heat-exchangers. The DEF pump is made from corrosion-resistant materials, such as 316 stainless steel, carbon-filled PEEK plastic... the gears comprise 30 percent carbon-filled PEEK plastic
Implementation Method 2
The DEF pump includes a pressure sensor integrated into the outlet side of the pump to allow the pump controller to determine if the pump has been running while dry for an excessive amount of time
Implementation Method 3
the microcontroller controls circulation of diesel exhaust fluid through the cooling pipe to pull heat away from the inverter assembly
Implementation Method 4
The DEF pump pulls DEF from a large tank, or reservoir, (e.g., a main DEF tank), pumps DEF to a smaller tank, or reservoir, such as a dosing tank, pressurizes the inlet of the smaller tank
Data Source
AI summary
The present invention relates to a diesel exhaust fluid (DEF) pump, DEF pump system and method for use of a DEF pump in cleaning the exhaust from diesel and diesel-electric engines. The DEF pump includes a plurality of gears, a pump housing, wear plate, pump body cover, a pump body insert, inverter assembly, inverter housing, speed sensor, pressure sensor, controller area network (CAN) connector, inverter cooling pipe, mounting feet or base plate, inlet, outlet, lifting ring, power connector, and motor. The DEF pump system includes a DEF pump, a main DEF tank, a dosing tank, a selective catalytic reduction (SCR) system, a flow control valve, and a relief valve. The DEF pump pulls DEF from a large tank, pumps DEF to a smaller tank injects DEF from the small tank into the exhaust stream where some of the DEF is consumed, and circulates unused DEF back to the large tank.