Throttle Valve Control for DPF Regeneration Hysteresis
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Solution Overview
Problem
The hysteresis in throttle valves, particularly intake and exhaust throttle valves, leads to discrepancies between instructed and actual opening degrees, causing either insufficient or excessive exhaust gas flow rates, which can result in engine failure or hinder the effective operation of diesel particulate filter (DPF) forced regeneration.
Innovation Solution
A control device and method that includes a hysteresis occurring condition determination unit and a hysteresis elimination execution unit to temporarily adjust the throttle valve opening degree to align it with the instructed degree, reducing the opening difference and maintaining optimal exhaust gas flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the catalyst converter is made large to ensure complete purification of unburned hydrocarbons and CO, then the exhaust gas purification performance is improved, but the device size and vehicle installation space requirements increase
Solution Approach 1:
The patent changes the chemical parameters of exhaust gas by controlling the air-fuel ratio to achieve a lean-burn condition (excess air). This parameter change enables the catalyst converter to operate more efficiently, achieving complete purification of unburned hydrocarbons and CO at a smaller size by optimizing the combustion characteristics before the exhaust enters the catalyst.
Solution Approach 2:
The patent applies preliminary action by pre-mixing excess air with the fuel-air mixture before combustion occurs in the cylinder. This preliminary preparation of the exhaust gas composition (creating a lean burn condition) ensures that when the exhaust reaches the catalyst converter, the purification process is more effective and requires less catalyst volume.
2Reliability
If the air-fuel ratio is increased to reduce NOx emissions, then NOx purification is improved, but the combustion stability and unburned hydrocarbon oxidation efficiency deteriorate
Solution Approach 1:
The patent optimizes the air-fuel ratio parameter to a specific lean-burn range (excess air coefficient of 1.03-1.07) that simultaneously achieves good NOx reduction and maintains combustion stability. This precise parameter control allows the system to balance multiple emission requirements without sacrificing combustion reliability or hydrocarbon oxidation efficiency.
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
Prevents the operating range of DPF forced regeneration from being narrowed by eliminating hysteresis, ensuring consistent exhaust gas flow rates and preventing engine failure.
Implementation Method 1
a catalyst converter which purifies the exhaust gas from the internal combustion engine
Data Source
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AI summary
In an engine comprising a diesel oxidation catalyst and a diesel particulate filter disposed in an exhaust flow channel of the engine, a control device is configured so as to dictate the opening degree of a throttle valve provided to an intake flow channel or the exhaust flow channel of the engine. The control device comprises: a hysteresis occurrence condition determination unit that determines a hysteresis occurrence condition (the elapse of a prescribed time period during which the dictated opening degree of the throttle valve remains equal to or less than a prescribed opening degree, and/or the elapse of a prescribed time period during which the engine output remains equal to or less than a prescribed output); and a hysteresis-resolving operation execution unit that, when the hysteresis occurrence condition is determined to be fulfilled, causes the throttle valve to execute a hysteresis-resolving operation for temporarily increasing the opening degree of the throttle valve above the dictated opening degree and then returning the opening degree to the dictated opening degree.