Injector Closing Time Detection via Current Slope Discrimination
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Solution Overview
Problem
Existing selective catalytic reduction systems face challenges in accurately diagnosing injector faults and determining injector closing times without disrupting emissions control processes, particularly in diesel engine vehicles, which can lead to under-dosing of reductants and reduced DeNOx functionality.
Innovation Solution
A method and system using a digital filter and slope discriminator to detect the closing time of injector valves by monitoring injector current, allowing for accurate identification of stuck injectors without additional hardware and minimizing disruptions to emissions control, employing an engine control unit to process valve current profiles and determine stuck status and closing times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure changes are monitored after commanding the pump to run or shut down to identify faults, then diagnostic capability is improved, but the emissions control process is disrupted
Solution Approach 1:
The patent enables continuous monitoring of injector current during normal SCR operation to detect closing time and faults without interrupting the emissions control process. The controller continuously acquires current data and processes it through filtering and slope discrimination algorithms, allowing diagnostic functions to operate concurrently with the useful action of NOx reduction.
Solution Approach 2:
The patent uses injector current as an intermediary parameter to diagnose injector status without directly interfering with the emissions control process. By monitoring current characteristics and their derivatives, the system extracts diagnostic information about injector closing behavior while the injector continues to perform its primary function of delivering reductant.
2Measurement precision
If additional hardware is added to detect injector closing time accurately, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent utilizes existing injector current sensing capability to detect closing time, allowing the system to serve its own diagnostic needs without external measurement devices. The controller processes the current data that is already being acquired for injection control, extracting closing time information through signal processing algorithms rather than additional sensors.
Solution Approach 2:
The patent replaces potential mechanical or external sensing hardware with electronic signal processing of existing current data. By using digital filtering and slope discrimination on the current waveform, the system achieves precise closing time detection through computational methods rather than additional physical measurement devices.
Data Source
AI summary
A control unit, controller and non-transitory machine-readable medium for detecting a closing time of an injector valve are disclosed. The control unit is configured to receive a valve current profile of the injector valve, process the valve current profile using at least a slope discriminator, and determine a stuck status and a closing time (if applicable) of the injector valve based on an output of the slope discriminator.