Retention of Wires in Induction Heated Emissions Treatment Unit
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Solution Overview
Problem
Catalytic converters and particulate filters have low efficiency when cold, leading to increased harmful emissions during vehicle start-up due to the slow attainment of light-off temperature, where catalytic conversion processes are ineffective.
Innovation Solution
The implementation of induction heating using a metal coil and wires within the catalytic converter or particulate filter to generate a varying electromagnetic field, inducing eddy currents and resistive heating, which accelerates the warming of the substrate and catalyst, thereby speeding up the light-off process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If induction heating is implemented to rapidly heat the catalytic converter substrate, then the light-off temperature is achieved faster, but the wires used for heating may become dislodged during thermal expansion and contraction cycles
Solution Approach 1:
The wire is divided into multiple discrete sections along its length, with each segment independently retained within the substrate. This segmentation allows each segment to be secured separately, preventing complete wire dislodgement while accommodating thermal expansion and contraction of different portions of the wire during heating cycles.
Solution Approach 2:
The wire segments are pre-retained within the substrate before the induction heating process begins. This preliminary retention ensures that when rapid heating occurs and thermal expansion takes place, the wire segments are already secured in position and cannot become dislodged during the thermal cycles.
2Productivity
If rapid heating is applied to achieve light-off temperature quickly, then cold start emissions are reduced, but thermal stress and mechanical stress on the substrate and wires increase
Solution Approach 1:
Segmenting the wire into multiple sections distributes the thermal stress and mechanical stress along the length of the wire and substrate. Each segment can expand and contract independently within its retained position, reducing concentrated stress points that would otherwise compromise structural integrity during rapid heating and cooling cycles.
Solution Approach 2:
The induction heating system enables precise control of heating parameters such as power level, frequency, and duration. This allows the substrate to be heated rapidly to light-off temperature while managing the rate of temperature change to minimize thermal shock, and subsequently cooling the substrate in a controlled manner to reduce thermal stress on the structure and retained wire segments.
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 method quickly raises the temperature of the catalytic converter or particulate filter, enhancing the efficiency of pollutant conversion processes and reducing emissions during cold start-ups by ensuring rapid attainment of the light-off temperature.
Implementation Method 1
generation of a varying electromagnetic field by a metal coil to induce eddy currents and resistive heating
Implementation Method 2
induce eddy currents and resistive heating, which accelerates the warming of the substrate and catalyst
Data Source
AI summary
Techniques are disclosed to aid fixing of an elongate wire within an elongate, linear cell of a honeycomb ceramic substrate unit for a gaseous emissions treatment assembly. In one method, the wire is formed with a resiliently flexible element, and inserted into the cell, the insertion act causing the resiliently flexible element to flex and to cause a part of the element to bear against a wall of the cell and so provide frictional retention of the wire in the cell. In another, method, an adhesive is used either on the outside of the wire or the inside of the cell. In another method, the wire is scored at spaced intervals along its length to provide relief spaces for linear expansion of the wire to reduce stress at its interface with cell walls.