Piezo Fuel Injection Valve Timing Determination
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Solution Overview
Problem
Piezo fuel injection valves with direct drive face challenges in accurately determining the actual start of injection due to manufacturing tolerances and aging, which affect injection timing and quantity, leading to inefficiencies in internal combustion engine performance.
Innovation Solution
A method involving a test injection with a short activation duration to determine the closing time of the nozzle needle using capacitance measurements, allowing for calculation of the actual start of injection by accounting for known stroke speeds and using proportionality factors based on working pressure and other variables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If piezo fuel injection valves with direct drive are used to enable variable control of injection process, then injection control flexibility is improved, but manufacturing tolerances and aging cause variations in injection timing and quantity
Solution Approach 1:
The patent implements a feedback mechanism by measuring the actual start of injection through capacitance signal analysis and comparing it with the commanded injection timing. The control device calculates correction values based on the deviation between actual and expected injection timing, then applies these corrections to subsequent injections. This closed-loop feedback system compensates for variations caused by manufacturing tolerances and aging, maintaining reliable injection timing while preserving the flexibility of piezo direct drive control.
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 precise determination of the actual start of injection, improving injection accuracy and allowing for correction factors to enhance fuel quantity control, thereby optimizing engine performance.
Implementation Method 1
A piezo actuator allows conclusions to be drawn about force inputs based on its capacitance signal. Force inputs at the nozzle needle are therefore reflected in the piezo signal.
Implementation Method 2
piezo fuel injection valves, in which the spray holes of the valve for injecting the fuel into the combustion chamber are released by lifting a valve needle out of a valve needle seat... the piezo actuator only actuating a control valve for controlling the actuating pressure
Data Source
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AI summary
The method for determining the actual start of injection can be carried out by means of the actuating device for the piezo fuel injection valve and has the following steps. Firstly, a test injection is carried out with such a short actuation duration that a start of shut-off takes place at a time so early that the nozzle needle does not reach the open end position. Said time is predefined by the actuation and is therefore precisely known. In the next step, the closing time of the nozzle needle is then determined by measurement and evaluation of an electrical variable of the piezo direct drive. Once the closing time and the time of the start of shut-off are known, the actual start of injection is calculated back from the closing time via the start of shut-off. This permits an adequately precise determination of the actual injection quantity in almost every operating state of the internal combustion engine.