Injection Controller Air Mixing Detection
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Solution Overview
Problem
Existing exhaust purification systems, such as urea SCR systems, face challenges in accurately determining the presence of air in the reducing-agent passage, which affects the stability of urea water injection into the exhaust pipe, leading to unstable NOx reduction reactions.
Innovation Solution
An injection controller that acquires the variation in pump rotational speed caused by air entry into the reducing-agent passage, using this rotational variation as a parameter to determine air mixing, thereby ensuring precise detection and control of air presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If pressure feedback control is used to maintain constant pressure in the reducing-agent passage, then pressure stability is improved, but the ability to detect air mixing is worsened
Solution Approach 1:
The patent uses pump rotational speed as an intermediary parameter to detect air mixing. Instead of directly measuring pressure variations (which are suppressed by feedback control), the system measures the pump's rotational speed, which indirectly reflects pressure changes and air presence in the passage. This mediator allows detection without disrupting the pressure stability maintained by feedback control.
Solution Approach 2:
The patent replaces pressure-based detection with a mechanical/rotational speed-based detection system. By monitoring the pump's rotational speed variations rather than pressure variations, the system can detect air mixing while maintaining pressure stability through feedback control. The rotational speed measurements substitute for direct pressure measurements that would be obscured by feedback control.
2Reliability
If draw and return processing is executed to prevent urea water freezing, then reliability is improved, but air entry into the reducing-agent passage increases
Solution Approach 1:
The patent implements feedback control by monitoring pump rotational speed and using this information to detect air mixing. When air is detected through rotational speed variations, the system can respond by adjusting pump operations or preventing draw-and-return processing, thereby maintaining reliability while minimizing air entry. The feedback loop allows the system to adapt to air presence and prevent harmful effects.
Solution Approach 2:
The system uses the pump's own rotational speed measurements to detect air mixing and self-regulate its operation. By monitoring its own performance characteristics, the pump system can identify air presence and adjust operations to prevent freezing while minimizing air entrainment, making the system self-diagnosing and self-regulating.
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 solution allows for accurate determination of air mixing in the reducing-agent passage, stabilizing the injection quantity of urea water and enhancing the precision of NOx reduction reactions, even when the system controls pipe pressure within a predetermined range.
Implementation Method 1
a pump that pressurizes and pumps the reducing agent to the injector through a reducing-agent passage
Implementation Method 2
an injector that is located in an exhaust passage of an internal combustion engine and injects to supply a reducing agent in a liquid state
Implementation Method 3
the urea water injected from the injector into the exhaust pipe is hydrolyzed by an exhaust-gas heat to generate ammonia (NH3)
Implementation Method 4
the urea water injected from the injector into the exhaust pipe is hydrolyzed by an exhaust-gas heat
Implementation Method 5
the ammonia is adsorbed at the SCR catalyst
Implementation Method 6
a NOx purification catalyst that is a SCR catalyst in the exhaust pipe... the NOx in the exhaust gas is reduced at the SCR catalyst by a reduction reaction executed by the ammonia
Data Source
AI summary
An injection controller that is applied to an exhaust purification system including an injector that is located in an exhaust passage of an internal combustion engine and injects to supply a reducing agent in a liquid state to a NOx purification catalyst purifying NOx in an exhaust gas, and a pump that pressurizes and pumps the reducing agent to the injector through a reducing-agent passage. The injection controller includes an acquisition unit configured to acquire a variation quantity of a rotational speed of the pump caused in response to an injection of the injector or a correlation value that is a value correlative to the variation quantity, as a rotational variation parameter, and a determination unit configured to determine whether an air mixing exists in the reducing-agent passage based on the rotational variation parameter.