Common Rail Injector Timing via Pressure Signal Filtering
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Solution Overview
Problem
In internal combustion engines with common rail systems and individual accumulators, existing processes fail to accurately determine the start and end points of pre-injection and post-injection due to pressure oscillations caused by the mechanical closing of the injector needle, leading to incorrect conclusions about injection timing.
Innovation Solution
The process filters the individual accumulator pressure using a tunable filter like a comb filter, determining local minimum values to identify the end of post-injection and calculating virtual start points for pre-injection and post-injection based on mathematical functions, without requiring additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the individual accumulator pressure is measured directly during post-injection, then the injection timing can be detected, but the pressure oscillations caused by mechanical closing of the injector needle lead to incorrect conclusions about injection start and end points
Solution Approach 1:
The patent introduces an intermediary evaluation process that separates the raw pressure measurement from the injection timing determination. Instead of directly using the oscillating pressure signal, the method uses the pressure signal as an intermediary to derive timing information through comparison with theoretical pressure curves and pattern recognition, thereby eliminating the direct harmful effect of oscillations on measurement accuracy
Solution Approach 2:
The patent creates a theoretical copy of the expected pressure curve and compares it with the actual measured pressure signal. By copying the ideal pressure behavior and superimposing it with measured values, the system can identify injection events based on deviations from the theoretical curve rather than relying on the oscillating raw signal alone
2Measurement precision
If additional sensors are added to improve injection timing measurement, then measurement precision can be enhanced, but device complexity and cost increase
Solution Approach 1:
The patent makes the existing individual accumulator pressure sensor serve multiple functions. Instead of adding separate sensors for pre-injection, main injection, and post-injection detection, the system uses the single pressure sensor's signal evaluated through a sophisticated algorithm to determine all injection timing points, thereby eliminating the need for additional hardware
Solution Approach 2:
The patent transforms the single pressure sensor into a multi-functional measurement device. The same sensor that originally served for general pressure monitoring is now used universally for detecting pre-injection, main injection, and post-injection timing through advanced signal evaluation, making one component perform multiple measurement tasks
Data Source
AI summary
For an internal combustion engine with a common rail system including individual accumulators, a process for open- and closed-loop control is proposed, in which the individual accumulator pressure (pE) is detected within a measuring interval and stored, an absolute minimum value of the stored individual accumulator pressure (pE) is interpreted as the end of the main injection, and on the basis of the end of the main injection, a mathematical function is used to calculate a virtual starting time for the main injection. In the measuring interval after the end of the main injection, the individual accumulator pressure (pE) is filtered within a time window, a local minimum value of the filtered individual accumulator pressure is interpreted as the end of a post-injection, and a mathematical function is used to calculate a virtual start of the post-injection.