Solenoid Valve Event Detection Using Chopped Waveform Current Sampling
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Solution Overview
Problem
Existing methods for detecting the operational state of solenoid-operated reductant injectors, particularly in systems using chopped voltage/current waveforms, are ineffective due to difficulties in accurately determining valve opening or closing events.
Innovation Solution
A method involving applying a chopped voltage to the solenoid, sampling current at local maxima and minima, calculating the difference between these points, determining the rate of change, and analyzing derivatives to identify valve events, synchronized with the voltage drive modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a chopped voltage waveform is applied to the solenoid to actuate the valve, then the valve can be operated with reduced wear and improved control, but the detection of valve opening or closing events becomes difficult and inaccurate
Solution Approach 1:
The chopped voltage waveform is divided into discrete pulses, and the current response is sampled at specific segments (local maxima and minima) of each pulse cycle. This segmentation allows the system to capture valve state information at critical moments during the chopped waveform cycles, enabling accurate detection despite the discontinuous nature of the drive signal.
Solution Approach 2:
The method performs preliminary sampling of current at local maxima and minima before analyzing the valve state. By pre-identifying these critical points in the chopped waveform cycle and sampling current at these predetermined moments, the system prepares the necessary data for accurate valve event detection before the actual analysis occurs.
2Device complexity
If traditional current trace analysis is used to detect valve events, then the detection method is simple, but it fails to provide accurate detection when chopped voltage waveforms are applied
Solution Approach 1:
The detection method transitions from static analysis of continuous current traces to dynamic sampling at varying points within chopped waveform cycles. The sampling points (local maxima and minima) dynamically adapt to the chopped waveform structure, allowing the system to maintain detection accuracy while the waveform itself changes over time.
Solution Approach 2:
The method changes the analysis parameters from examining continuous current magnitude to calculating rates of change of current differences between sampled points. This parameter transformation converts the chopped waveform data into a form where valve opening and closing events produce distinct, detectable signals regardless of the waveform's discontinuous nature.
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
Enables accurate detection of valve opening and closing events even with chopped waveforms, improving operational state assessment and reducing wear on solenoid-operated reductant injectors.
Implementation Method 1
applying a voltage to said solenoid to actuate said valve
Data Source
AI summary
A method of detecting a valve opening or closing event in a solenoid operated reductant injector valve includes applying a voltage to the solenoid to actuate the valve, the voltage having a chopped waveform. A resultant current through the solenoid is sampled at local maxima and minima. Values of a difference between the local maxima and subsequent local minima or between local minima and subsequent local maxima are determined. A rate of change of the difference values are determined and a valve opening or closing event based on the rate of change is determined.