Urea Solution Temperature Control via PWM Valve Dynamics
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Solution Overview
Problem
The existing systems for managing the temperature of a urea solution in a urea solution tank for NOx purification treatment in internal combustion engines face challenges in suppressing air bubble formation and accurately determining the urea concentration, leading to delayed or insufficient thawing and improper NOx purification.
Innovation Solution
A system and method that control the flow rate of a heating medium, such as engine cooling water, through a flow control valve to regulate the temperature of the urea solution, setting specific valve-open time ratios based on temperature ranges to prevent air bubble formation and ensure accurate urea concentration determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the opening and closing valve is opened slowly or closed quickly to warm the urea solution, then the thawing of the urea solution is delayed or insufficient, but if the valve is closed slowly, air bubbles are formed in the urea solution
Solution Approach 1:
The patent applies dynamics by transitioning from static valve positioning to dynamic PWM control. The flow control valve is driven by a PWM signal whose duty cycle is adjusted based on temperature feedback, enabling the valve to dynamically modulate heating medium flow rate. This dynamic control allows the system to optimize both thawing efficiency and air bubble suppression by adjusting valve opening degree in real-time according to urea solution temperature conditions.
Solution Approach 2:
The patent implements feedback control through a temperature sensor that continuously monitors urea solution temperature and feeds this information back to the control unit. The control unit processes this feedback signal and adjusts the PWM duty cycle accordingly, creating a closed-loop control system. This feedback mechanism enables the system to automatically balance thawing requirements against air bubble formation prevention by adapting valve control based on actual temperature conditions.
2Productivity
If the valve opening timing is slow or closing timing is fast, then the thawing of the urea solution is delayed, but rapid valve response may cause temperature fluctuations
Solution Approach 1:
The patent employs periodic action through PWM (Pulse Width Modulation) control of the flow control valve. Instead of continuous analog control, the valve is driven by periodic pulse signals with variable duty cycles. This periodic control method enables rapid response for thawing while maintaining temperature stability through averaged flow control over multiple cycles, effectively resolving the contradiction between fast thawing speed and temperature control stability.
Solution Approach 2:
The system uses dynamic PWM duty cycle adjustment to balance thawing speed and temperature stability. The control unit dynamically modifies the duty cycle based on temperature feedback, enabling the valve to respond rapidly when heating is needed while providing smoothed, stable control during maintenance phases. This dynamic modulation resolves the contradiction by allowing fast response characteristics when required while maintaining overall temperature stability.
3Duration of action of stationary object
If the temperature of the urea solution increases rapidly, then the thawing efficiency is improved, but air bubbles are formed making it difficult to accurately determine the concentration of urea
Solution Approach 1:
The patent uses feedback control to prevent air bubble formation while maintaining thawing efficiency. The temperature sensor continuously monitors urea solution temperature, and the control unit adjusts the PWM duty cycle based on this feedback to prevent excessive temperature rise. This feedback mechanism ensures the temperature increases at an optimal rate that maintains thawing efficiency without causing air bubble formation that would interfere with concentration measurement accuracy.
Solution Approach 2:
The system dynamically adjusts the heating rate through PWM control to optimize the balance between thawing efficiency and measurement accuracy. By modulating the valve duty cycle dynamically, the system can apply aggressive heating when needed for efficient thawing, then transition to gentler control as the urea solution approaches the target temperature, preventing air bubble formation that would compromise concentration determination 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 approach effectively suppresses air bubble formation, secures the thawing property of the urea solution, and accurately determines the urea concentration, enabling precise NOx reduction by ensuring a proper amount of urea solution is supplied for effective purification treatment.
Implementation Method 1
thaw or keep warm a urea solution stored in a urea solution tank by flowing a heating medium to pass through the urea solution tank
Implementation Method 2
flowing a heating medium to pass through the urea solution tank
Data Source
AI summary
A system and method for managing the temperature of a urea solution are thereby provided, in which air bubble formation in the urea solution caused by increases in the urea solution temperature is suppressed while thawing of the urea solution stored in the urea solution tank and used for NOx purification treatment is ensured, the concentration of the urea contained in the urea solution is accurately determined, and NOx is precisely reduced.