SCR NOx Sensor Heater Control for Battery Load Reduction
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Solution Overview
Problem
The existing SCR systems for diesel vehicles face challenges in reducing the battery burden from heater energization and extending the time during which NOx concentration cannot be detected, due to high power consumption and insufficient battery charge, especially during engine start-up and low engine rotation.
Innovation Solution
An SCR system with an energization permission unit that prohibits heater energization at engine start and permits it when engine revolutions exceed a threshold value for a stabilization wait time, and prohibits energization during low engine rotation for a recovery wait time, ensuring efficient battery charging and reducing NOx detection downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a heater that generates a large amount of heat is used to raise the NOx sensor temperature quickly, then the sensor operating temperature is reached in a short period, but the heater significantly consumes power and creates large current demand on the battery
Solution Approach 1:
The system performs preliminary warming of the NOx sensor using a heater before the engine starts operating. The energization permission unit allows heater operation only when engine revolutions are above a threshold, ensuring the sensor is warmed up in advance during engine startup phase, so that NOx detection can begin promptly without requiring excessive power during critical engine start-up periods
Solution Approach 2:
The system dynamically controls heater operation based on real-time engine revolution detection. The energization permission unit monitors engine revolutions and permits or prohibits heater energization accordingly, creating a dynamic control strategy that adapts power consumption to engine operating conditions, allowing fast warming when engine is running but preventing excessive draw during startup
2Speed
If the heater current is increased to reduce warming time, then the sensor reaches operating temperature faster, but the battery voltage may be lowered below operation-guaranteed voltage during cranking, causing control circuit stoppage and engine failure to start
Solution Approach 1:
The system performs preliminary warming of the NOx sensor using a heater before the engine starts operating. The energization permission unit allows heater operation only when engine revolutions are above a threshold, ensuring the sensor is warmed up in advance during engine startup phase, so that NOx detection can begin promptly without requiring excessive power during critical engine start-up periods
Solution Approach 2:
The energization permission unit acts as an intermediary between the heater control and the battery power supply. It monitors engine revolutions and mediates heater operation to ensure that power is drawn only when the engine is running and can supply its own power, thereby protecting the battery from excessive discharge during cranking while still enabling timely sensor warming
3Use of energy by stationary object
If the heater energization is stopped frequently to conserve battery power, then battery charge is maintained, but the NOx sensor temperature falls below operating temperature and NOx concentration cannot be detected for extended periods
Solution Approach 1:
The system performs preliminary warming of the NOx sensor using a heater before the engine starts operating. The energization permission unit allows heater operation only when engine revolutions are above a threshold, ensuring the sensor is warmed up in advance during engine startup phase, so that NOx detection can begin promptly without requiring excessive power during critical engine start-up periods
Solution Approach 2:
The system uses feedback from the NOx sensor detection status to control heater operation. When the sensor reaches operating temperature and NOx detection becomes possible, the system can stop heater energization. The feedback mechanism ensures continuous operation only when necessary, balancing battery power conservation with maintaining detection capability
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 reduces battery burden and shortens the time NOx concentration cannot be detected, allowing for more frequent and effective urea solution injection control and ideal exhaust gas purification.
Implementation Method 1
it is necessary to make current flow in an electric heater attached to the NOx sensor to heat the NOx sensor to the sensor operating temperature
Implementation Method 2
reduces NOx on an SCR catalyst to purify NOx
Implementation Method 3
supplies urea solution to an exhaust gas upstream of the SCR device to generate ammonia using heat of the exhaust gas
Data Source
AI summary
A selective catalytic reduction system (SCR) that reduces a burden on a battery resulting from energization of a heater and a decrease in time during which an NOx concentration cannot be detected. The SCR system includes: an SCR device; a dosing valve; NOx sensors; an urea solution injection control unit; electric heaters for raising respective temperatures of the NOx sensors to a sensor operating temperature; and an energization permission unit that prohibits energization of the heaters at the time of a start of an engine and permits energization of the heaters when engine revolutions become equal to or exceed a preset energization permission threshold value and such state lasts for a period of time equal to or exceeding a preset stabilization wait time.