Reducing Agent Supply Pressure Control via Throttle Valve
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Solution Overview
Problem
Existing reducing agent supply apparatuses for internal-combustion engine exhaust gas purification systems face challenges in maintaining target reducing agent pressure, leading to deviations and decreased diagnostic accuracy when injection amounts significantly change.
Innovation Solution
Incorporating a passage throttle valve with controlled opening adjustments based on the operation amount of the reducing agent injection valve, in conjunction with feedback-control of the pump output, to maintain target pressure and prevent large deviations in reducing agent pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback-control of pump output is used to maintain target reducing agent pressure, then pressure control is achieved, but large pressure deviations occur when injection amount significantly increases or decreases
Solution Approach 1:
A passage throttle valve is introduced as an intermediary component in the return passage to mediate pressure control. The valve adjusts return flow based on injection valve operation amount, preventing large pressure deviations when injection amount changes significantly, thereby stabilizing supply pressure without directly controlling pump output
2Adaptability or versatility
If reducing agent injection valve operation amount changes significantly, then injection control flexibility is improved, but pressure deviation from target pressure increases
Solution Approach 1:
The control unit receives signals about the injection valve operation amount and uses this feedback to proactively adjust the passage throttle valve opening. This feedback mechanism allows the system to anticipate pressure changes and compensate in advance, maintaining pressure stability even when injection amount changes significantly
3Reliability
If passage throttle valve opening is adjusted according to injection valve operation amount, then pressure stability is improved, but device complexity increases
Solution Approach 1:
The control unit integrates multiple functions: it controls both the injection valve and the passage throttle valve, and receives pressure sensor feedback. By merging these control functions into a single control unit, the system manages the additional complexity efficiently while achieving superior pressure control accuracy
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 configuration ensures accurate injection of liquid reducing agent in proportion to NOx levels, enhances diagnostic control precision, and reduces pressure deviations, thereby improving the efficiency and accuracy of exhaust gas purification.
Implementation Method 1
feedback-controlling the output of the pump based on the difference between the reducing agent pressure and the target pressure
Implementation Method 2
a passage throttle valve control means for controlling the opening of the passage throttle valve according to the change in the operation amount of the reducing agent injection valve
Data Source
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AI summary
A reducing agent supply apparatus that can reduce the state of large deviation of the pressure within a reducing agent supply passage from a target pressure and an exhaust gas purification apparatus including such a reducing agent supply apparatus are provided. A reducing agent supply apparatus including a pump, a reducing agent injection valve, a reducing agent supply passage, a reducing agent return passage and a pressure sensor, in which injection control of the liquid reducing agent by the reducing agent injection valve is performed while the reducing agent pressure is controlled so as to be maintained at a predetermined target pressure, includes: a passage throttle valve provided on the reducing agent return passage and having an opening controlled by energization; a pump control means for feedback-controlling the output of the pump based on the difference between the reducing agent pressure and the target pressure; and a passage throttle valve control means for controlling the opening of the passage throttle valve according to the change in the operation amount of the reducing agent injection valve.