Motorised Fluid Pump Overmolding for Rapid Urea Heating
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Solution Overview
Problem
Existing motorized pumps for urea-based selective catalytic reduction (SCR) systems struggle to rapidly heat the reducing agent within the pump body to its melting point, especially at ambient temperatures below -15°C, leading to delayed fluid pumping.
Innovation Solution
The use of an overmolded stator assembly with enhanced thermal conductivity, which fills the interdental spaces between stator teeth and directly contacts the pump container, allowing for rapid heat transfer via Joule and inductive effects to liquefy the urea within the pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stator and pump body are isolated by a thick container and air gap, then the motor is protected from corrosion by the urea mixture, but the heating of the reducing agent in the pump body becomes slow
Solution Approach 1:
A thermally conductive intermediary material is introduced between the stator and the pump container to facilitate heat transfer. This intermediary acts as a thermal bridge, allowing heat generated by the stator coils to efficiently reach the urea mixture in the pump body while maintaining the protective isolation between the motor components and the corrosive fluid.
Solution Approach 2:
The solution employs composite construction by combining the stator assembly with a thermally conductive material that has both high thermal conductivity and corrosion resistance. This composite structure enables simultaneous achievement of heat transfer efficiency and protection from the corrosive urea environment.
2Temperature
If flexible resistive tracks are used to heat the urea tank, then the urea can be heated to melting point, but the reducing mixture in the pump body cannot be rapidly heated
Solution Approach 1:
The stator assembly serves as a thermal intermediary that directly couples heat to the pump container. By positioning the stator in thermal contact with the container through a thermally conductive interface, the system efficiently transfers heat from the motor coils to the urea mixture in the pump body, overcoming the limitation of remote heating methods.
Solution Approach 2:
The stator assembly performs dual functions: it generates the magnetic field necessary for motor operation and simultaneously serves as a heating element for the urea mixture. This multi-functionality eliminates the need for separate heating systems and ensures rapid heating of the reducing agent in the pump body.
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
This approach significantly reduces heating time by up to a factor of 2, enabling quicker fluid pumping by ensuring the reducing agent remains in a liquid state within the pump body.
Implementation Method 1
by the Joule effect, this layer will heat the urea
Implementation Method 2
an overmolding of the stator having a conductivity higher than that of air, this overmolding advantageously making it possible to fill the space between the teeth of the stator to form a thermal diffusion body
Implementation Method 3
heating the urea mixture using the heat dissipated by the Joule effect in the coils of the electric motor
Data Source
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AI summary
The invention relates to a motorised pump (1) for pumping a fluid comprising an electric motor and made up of a container (20) and a stator assembly (2), said stator assembly (2) having a set of ferromagnetic sheets forming teeth extending radially and defining inter-tooth spaces and an inner space, said teeth each or partially supporting electric windings, said container (20) being housed in said inner space, hermetically isolated from said stator assembly (2), and comprising a rotor made up of an alternation of magnetised poles, the container (20) being made up of a shell (21) enclosing said rotor, a pumping element actuated by said rotor, and channels (16, 17) for circulating said fluid allowing the circulation of said fluid towards and out of the pumping element, characterised in that the stator assembly (2) has an overmoulding made of plastic material having a thermal conductivity coefficient higher than that of air, in that said overmoulding encompasses all the sheets and the electric windings, and in that it fills the inter-tooth spaces.