Piezoelectric Fuel Injector Needle Control via Hydraulic Amplification
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Solution Overview
Problem
Existing fuel injectors for diesel engines face challenges in achieving precise control over fuel injection due to stringent emission regulations, requiring improved accuracy and efficiency while maintaining engine performance.
Innovation Solution
A fuel injector design incorporating a piezoelectric actuator directly connected to a control piston, amplifying the movement of an injector needle arrangement through a cylinder space, which is in flow communication with the fuel space, allowing for precise control of fuel injection without additional control oil systems and protecting the actuator from fuel contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a piezoelectric actuator is used to control the injector needle, then the accuracy and speed of fuel injection control is improved, but the device complexity increases
Solution Approach 1:
The patent combines the piezoelectric actuator, control piston, and injector needle into a single integrated assembly where the actuator is directly connected to the control piston which in turn is connected to the injector needle. This merging eliminates the need for separate control systems and reduces overall device complexity while maintaining precise control capability.
Solution Approach 2:
The patent uses fuel pressure as a hydraulic medium to actuate the injector needle. The high-pressure fuel from the fuel inlet directly pushes the needle to open the orifice, eliminating the need for additional control oil systems or complex mechanical linkages. This hydraulic approach simplifies the actuation mechanism while improving response speed and control accuracy.
2Speed
If the injector needle is guided hydraulically by fuel pressure, then the response speed is improved, but the control precision deteriorates
Solution Approach 1:
The patent incorporates a spring element that provides a restoring force on the injector needle, creating a feedback mechanism. The spring ensures the needle returns to its closed position after fuel injection, providing precise control over the injection duration. This elastic feedback complements the hydraulic actuation to achieve both fast response and precise control.
Solution Approach 2:
The patent creates a dynamic system where the injector needle position is determined by the balance between hydraulic pressure (opening force) and spring force (closing force). This dynamic equilibrium allows the needle to respond quickly to pressure changes while maintaining precise control over the injection event duration through the interplay of these two forces.
3Productivity
If the cylinder space is filled with fuel for movement amplification, then the productivity is improved, but the risk of fuel leakage increases
Solution Approach 1:
The patent extracts the harmful aspect of fuel in the cylinder space by providing a dedicated discharge duct that channels any fuel leaking from the fuel space away from critical components. This extraction of the potential harmful element (leaking fuel) and its directed disposal prevents damage while maintaining the productivity benefits of fuel-filled cylinder space for movement amplification.
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 design enhances the accuracy, speed, and durability of fuel injection, reducing leakage and maintaining clean moving parts, while allowing for proportional movement of the injector needle arrangement, thus improving engine performance and compliance with emission regulations.
Implementation Method 1
a piezoelectric actuator arranged to control the position of the injector needle arrangement
Implementation Method 2
a spring element forcing the injector needle towards a position closing the nozzle orifice
Implementation Method 3
a fuel inlet for admission of pressurized fuel into the fuel space
Data Source
Figure 1
Figure 2
AI summary
Invention relates to a fuel injector (10) for an internal combustion piston engine comprising an injector body (12) provided with a fuel space (14) in the body (12), a fuel inlet (16) for admission of pressurized fuel into the fuel space (14), at least one nozzle orifice (18) through which fuel may be injected into a cylinder (20) of the engine, an injector needle arrangement (22), the a first end (21) of which is arranged in co-operation with the nozzle orifice (18) for opening or closing the orifice (18), a spring element (24) forcing the injector needle arrangement (22) towards a position closing the nozzle orifice (18), and a piezoelectric actuator (26) arranged to control the position of the injector needle arrangement (22) so as to control opening and closing of a flow communication from the fuel space (14) through the at least one nozzle orifice (18).