Exhaust Particle Filter Ash Detachment via Flow Speed
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Solution Overview
Problem
The accumulation of ash in exhaust particle filters of diesel engines leads to increased flow resistance and back-pressure, which cannot be effectively reduced by conventional soot oxidation methods, ultimately rendering the filters unusable.
Innovation Solution
A method that continuously monitors ash and soot accumulation, switching to a special operating mode to detach and transport ash from the channel walls to the filter's end, reducing flow resistance by maintaining a minimum exhaust flow speed and performing soot regeneration operations to lower soot levels, thereby extending the filter's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional soot oxidation operations are performed to reduce soot loading, then soot particles are removed from the exhaust particle filter, but ash accumulation increases flow resistance and ultimately renders the filter unusable
Solution Approach 1:
The patent changes the physical parameters of exhaust flow by increasing exhaust flow velocity through engine operating mode changes. This velocity increase creates shear forces that detach ash particles from channel walls and transport them to inlet channel ends, where they accumulate in a controlled manner that maintains filter usability while managing flow resistance
Solution Approach 2:
Instead of attempting to remove ash through oxidation (which cannot decompose inorganic ash), the patent inverts the approach by using flow dynamics to transport ash to specific locations (inlet channel ends) where accumulation is tolerable. This transforms the harmful distributed ash deposition into a controlled localized accumulation that preserves filter function
2Object-affected harmful factors
If ash accumulates on channel walls distributed across the length of the channel, then flow resistance increases significantly, but if ash accumulates at the end of inlet channels, then flow resistance increase is reduced
Solution Approach 1:
The patent applies local quality by creating different ash accumulation zones within the filter. Ash is deliberately transported and accumulated at inlet channel ends (specific locations) rather than being distributed uniformly across channel walls. This localized accumulation strategy reduces the overall impact on flow resistance while maintaining filter effectiveness in other regions
3Object-affected harmful factors
If the vehicle is serviced with reverse flow blowing to remove ash, then flow resistance is reduced and the filter becomes available for further use, but the method is costly and requires interruption of driving operation
Solution Approach 1:
The patent enables the exhaust particle filter to self-clean during normal driving operation by utilizing the engine's own exhaust flow. By switching to a high-velocity exhaust mode, the system creates self-generated shear forces that detach and transport ash particles without external intervention, eliminating the need for costly service interruptions and reverse flow blowing operations
4Object-affected harmful factors
If exhaust flow speed is increased to detach and transport ash, then ash accumulation is reduced and flow resistance decreases, but engine operation must be changed to a special operating mode
Solution Approach 1:
The patent implements periodic action by alternating between normal engine operating modes and special high-velocity exhaust modes. The control unit monitors ash accumulation and periodically triggers brief high-velocity events to detach and transport ash particles, then returns to normal operation. This periodic intervention maintains low flow resistance without requiring continuous special operating conditions
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 method effectively reduces flow resistance and extends the service life of the exhaust particle filter by strategically managing ash and soot accumulation, allowing for continued efficient engine operation without costly interruptions.
Implementation Method 1
detachment of ash attached to the channel walls of the exhaust particle filter and transportation of detached ash in the direction of the respective inlet channel end is made possible
Implementation Method 2
oxidation of the soot particles, for example by burning-off with oxygen present in the exhaust
Data Source
AI summary
A method for operating a motor vehicle internal combustion engine with an exhaust system branch in which a wall-flow exhaust particle filter is arranged. An amount of ash and an amount of soot accumulated in the exhaust particle filter are continuously determined. An ash increase value characterizing an increase in the amount of ash is determined and if pre-set conditions are present, the operation of the internal combustion engine is changed over to a special operating mode for performing an ash detachment and transportation operation, in which operating variables of the internal combustion engine are set such that, on the exhaust entry side in the exhaust particle filter, a pre-settable minimum exhaust flow speed results at which detachment of ash attached to the channel walls of the exhaust particle filter and transportation of detached ash in the direction of the respective inlet channel end is made possible.