Electroinjector Needle Control via Segmented Electrical Commands
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Solution Overview
Problem
Existing fuel-injection systems for internal-combustion engines struggle to achieve a fuel flow rate curve with two distinct constant levels, are complex to calibrate, and cannot adapt to engine operating conditions, leading to suboptimal performance and difficulty in producing consistent injector profiles.
Innovation Solution
An electroinjector system with a mobile needle controlled by an electromagnet and spring mechanism, utilizing calibrated diameters and ratios to modulate the needle's displacement in response to electrical commands, allowing for precise control of fuel injection profiles without mechanical calibration, enabling a stepwise flow rate curve with two levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dedicated injectors with multiple springs or coaxial springs are used to achieve a stepwise flow-rate curve, then the flow-rate profile can be approximated, but the calibration becomes complex and the device structure becomes more complicated
Solution Approach 1:
The injection event is segmented into multiple independent electrical commands (first command for pre-injection, second command for main injection) that are issued in succession. This segmentation allows control of different flow-rate levels through temporal separation rather than mechanical complexity, achieving the stepwise curve without multiple springs or complex calibration.
Solution Approach 2:
The patent replaces the mechanical spring-based needle control system with an electrical control system. Instead of using multiple preloaded springs with different characteristics to lift the needle to different positions, the system uses electrical commands that control a pintle valve to modulate fuel pressure in the control chamber, thereby controlling needle displacement electronically.
2Manufacturing precision
If springs are calibrated to obtain a specific flow-rate law, then the injection profile can be controlled, but the law cannot be modified according to variations of engine operating conditions
Solution Approach 1:
The system transitions from a static mechanical calibration (fixed spring characteristics) to a dynamic electrical control system. The duration and timing of electrical commands can be dynamically adjusted based on engine operating conditions, allowing the injection profile to adapt in real-time without physical recalibration.
Solution Approach 2:
The control system changes parameters (duration and timing of electrical commands) to adapt the injection profile to different operating conditions. By varying the duration of the first and second electrical commands, the system can achieve different pre-injection and main injection characteristics suitable for various engine loads and speeds.
3Manufacturing precision
If the needle displacement law is established for a given supply pressure, then the flow-rate curve can be achieved, but the law cannot be modified when supply pressure varies
Solution Approach 1:
The system uses feedback from the control chamber pressure (mediated through the pintle valve) to control needle displacement. By regulating the pressure in the control chamber through electrical commands, the system compensates for variations in supply pressure and maintains consistent needle displacement characteristics across different operating conditions.
4Device complexity
If pre-injection and main injection are controlled by a single electrical command, then the system is simpler, but situations arise where a pre-injection cannot be obtained
Solution Approach 1:
The single electrical command is segmented into two distinct commands issued in succession: a first electrical command for pre-injection and a second electrical command for main injection. This segmentation ensures that pre-injection can always be executed by controlling the duration and timing of the first command, while the second command provides the main injection, eliminating the reliability issue of missing pre-injection.
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
The system effectively achieves a stepwise fuel flow rate curve with two distinct levels, simplifying calibration and adapting to engine conditions, enhancing engine efficiency and consistency of fuel injection profiles.
Implementation Method 1
an electroactuator device (8), and an atomizer comprising an injection nozzle (5) and a needle (7) that is mobile along an opening stroke and a closing stroke for opening/closing the nozzle (5) under the control of the device (8)
Implementation Method 2
The needle (7) is mobile in an axial seat (9) for opening/closing the nozzle (5) under the control of an electroactuator device (8)
Data Source
AI summary
A fuel-injection system in an internal-combustion engine is provided with an electroinjector (1) comprising an injection nozzle (5), and a needle (7) mobile along an opening stroke and a closing stroke for opening/closing the nozzle (5) under the control of an electroactuator device (8). The opening stroke of the needle (7) is controlled by a rod (14) pushed by the pressure of the fuel in a control chamber (15), in such a way as to keep the needle (7) normally in the position for closing the nozzle (5). The control chamber (15) is equipped with an inlet duct (18) having a pre-set diameter (D4) and with an outlet passage (24) having a diameter (D5) and controlled by a control valve (16). The method for controlling fuel injection comprises the steps of choosing the ratio (D5/D4) of the aforesaid diameters so as to determine a certain rate of displacement of the needle (7), and issuing to the device (8) a first electrical command (C1) and a second electrical command (C2) sufficiently close to one another to displace the needle (7) with a profile of motion (P) without any discontinuities in time.