Elastic Nozzle Needle for Rapid Fuel Injection
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Solution Overview
Problem
Existing fuel injection nozzles for internal-combustion engines face challenges in achieving rapid needle opening and closing speeds, leading to inadequate fuel atomization and increased hydrocarbon emissions due to the limitations in pressure drop rates within the control chamber, which also result in stroke-to-stroke scatter of the injected fuel quantity.
Innovation Solution
The design incorporates an elastic longitudinal portion in the nozzle needle with a longitudinal stiffness of less than 40,000 N/mm, allowing for a snap-action effect that enhances the opening and closing speeds of the nozzle needle, thereby reducing the seat-throttle region duration and improving fuel atomization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the outflow throttle cross-section is enlarged to increase needle opening speed, then the needle opening speed is improved, but the injected fuel quantity becomes sensitive to actuation time causing large stroke-to-stroke scatter
Solution Approach 1:
The nozzle needle is designed with a longitudinally elastic portion that allows dynamic deformation during operation. The elastic portion has a longitudinal stiffness of less than 40,000 N/mm, enabling the needle to flex and store elastic energy during pressure changes, which smooths out rapid pressure drops and reduces sensitivity to actuation timing variations.
Solution Approach 2:
The invention changes the mechanical parameter of the nozzle needle by introducing an elastic portion with specific stiffness characteristics. This parameter change allows the needle to respond more gradually to pressure changes in the control chamber, transforming the system's dynamic response and reducing the harmful effects of rapid pressure drops on injection quantity consistency.
2Speed
If the pressure in the control chamber drops rapidly to increase needle opening speed, then the needle opening speed is improved, but the ballistic mode of operation is lost and the needle reaches the mechanical stroke stop prematurely
Solution Approach 1:
The elastic longitudinal portion of the nozzle needle provides dynamic compliance that moderates the needle's response to rapid pressure changes. The needle can deform elastically during the pressure drop, storing energy that is released to maintain controlled motion and preserve the ballistic mode of operation even when the control chamber pressure drops rapidly.
Solution Approach 2:
The elastic portion of the nozzle needle acts as a cushioning element that absorbs and moderates the effects of rapid pressure changes before they fully impact the needle's mechanical motion. This beforehand cushioning prevents the needle from reaching the mechanical stroke stop too early while maintaining rapid opening capability.
3Reliability
If the nozzle needle moves away from the nozzle seat slowly, then the seat-throttle region is extended, but fuel atomization is inadequate and hydrocarbon emissions increase
Solution Approach 1:
The elastic longitudinal portion enables the nozzle needle to undergo dynamic deformation that accelerates its opening motion. The needle rapidly moves away from the nozzle seat by utilizing elastic recovery, which minimizes the duration of the seat-throttle region and ensures adequate fuel atomization without increasing hydrocarbon emissions.
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 design ensures rapid and consistent fuel injection with improved atomization, reducing noxious emissions and minimizing stroke-to-stroke scatter in fuel quantity, while maintaining the stability and manufacturability of the nozzle needle.
Implementation Method 1
The nozzle needle has a longitudinally elastic portion having a longitudinal stiffness of less than 40,000 N/mm
Implementation Method 2
a control chamber which can be filled with fuel under high pressure, in which a variable pressure can be set and on the end surface of which a force can be exerted in the direction toward the nozzle seat by the hydraulic pressure
Data Source
AI summary
The invention relates to an injection nozzle (1) for fuels, comprising a nozzle body (2), in which a pressure chamber (4) that can be filled with fuel under high pressure is formed, in which pressure chamber a piston-shaped nozzle needle (3) is arranged in such a way that the nozzle needle can be moved longitudinally. A sealing surface (6) is formed at one end of the nozzle needle (3) and an end face (9) is formed at the opposite end, wherein the sealing surface (6) interacts with a nozzle seat (5) in order to open and close at least one injection opening (8). A control chamber (10) that can be filled with fuel under changing pressure is bounded by the end face (9) of the nozzle needle (3) such that a force can be applied to the end face (9) in the direction of the nozzle seat (5) by means of the hydraulic pressure. The nozzle needle (3) has an elastic longitudinal segment (25), which has a longitudinal stiffness of less than 40,000 N/mm.