Fuel Injector Needle Timing Detection via Piezo Pressure Sensing
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Solution Overview
Problem
In common rail injectors, deviations in the opening and closing times of the nozzle needle due to component wear, manufacturing tolerances, and pressure waves lead to inaccuracies in fuel injection, affecting the injected fuel quantity, which existing methods fail to accurately detect and correct.
Innovation Solution
A method that qualitatively senses the pressure in the control chamber to detect the closing time of the nozzle needle, using a piezo element to determine the pressure gradient and zero crossings, allowing for precise correction of inaccuracies across the entire switching chain, applicable to both solenoid and piezo actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing detection methods (pressure sensor in nozzle chamber, armature collision detection) are used to detect injection timing, then the basic function of detecting opening/closing times is achieved, but inaccuracies in fuel injection quantity occur due to component wear, manufacturing tolerances, and pressure waves
Solution Approach 1:
A piezoelectric sensor is introduced as an intermediary measurement element that indirectly detects nozzle needle position through pressure gradient measurements in the control chamber. This mediator converts mechanical pressure changes into electrical signals, enabling precise detection without direct contact with the high-pressure fuel system or moving needle parts.
Solution Approach 2:
The invention replaces direct mechanical detection methods (such as armature collision detection or direct needle position sensors) with a piezoelectric sensing system that measures pressure gradients. This substitution eliminates mechanical wear, reduces complexity, and provides more reliable detection of nozzle needle opening and closing events.
2Loss of information
If a pressure sensor is arranged in the nozzle chamber to detect injection start and end, then basic timing detection is achieved, but the system cannot detect faults or deviations within the high-pressure hydraulic system
Solution Approach 1:
The piezoelectric sensor acts as an intermediary measurement point in the control chamber that indirectly monitors the entire high-pressure hydraulic system's behavior. By measuring pressure gradients, it provides information about nozzle needle movement and system deviations without requiring direct sensors in the high-pressure fuel lines or nozzle chamber.
Solution Approach 2:
The invention extracts the measurement function from the high-pressure fuel system environment and places it in the control chamber environment. This extraction allows detection of system behavior while avoiding the complexities and risks associated with placing sensors directly in the high-pressure hydraulic system.
3Reliability
If component wear and manufacturing tolerances are accepted as unavoidable, then device simplicity is maintained, but significant influences on injected fuel quantity occur due to timing deviations
Solution Approach 1:
The piezoelectric sensor provides real-time feedback signals about nozzle needle opening and closing events. This feedback enables the control system to detect timing deviations caused by wear or manufacturing tolerances and compensate for them, maintaining consistent fuel injection quantity over the component service life.
Solution Approach 2:
The system performs preliminary detection of nozzle needle movement timing using the piezoelectric sensor during normal operation. By continuously monitoring opening and closing times, the system can identify deviations before they significantly impact fuel injection accuracy, allowing for corrective actions or compensations.
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 method enables precise determination of the injected fuel quantity by compensating for manufacturing tolerances and drift over time, as well as variable boundary conditions, ensuring accurate fuel injection by detecting the opening and closing times of the nozzle needle.
Implementation Method 1
using a piezo element to determine the pressure gradient and zero crossings
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a method for determining a point in time when a valve needle arranged in an injection valve changes directions. In said method, a variable providing information on a curve indicating the pressure (40) in a control chamber of the injection valve is directly measured using a sensor in the control chamber, and from said variable providing information on the pressure curve (40), it is determined at what point in time the curve is at an extreme point, and said point in time is identified as the point in time when the direction changes.