Fluid Injector Valve Needle Damping Control
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Solution Overview
Problem
Existing injectors for internal combustion engines face challenges in controlling the amount of injected fluid, particularly under high pressure, leading to inefficiencies and uncontrollable fluid injection.
Innovation Solution
The design incorporates a valve assembly with a solid valve needle, an armature retainer, and an electromagnetic actuator, featuring a hydraulically effective restriction between the armature retainer and pole piece constriction surfaces, which reduces the hydraulic diameter as the valve needle displaces, generating a damping force to control fluid injection velocity and amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the valve needle is displaced rapidly to enable efficient operation, then the injection speed is improved, but the controllability of the injected fluid amount deteriorates
Solution Approach 1:
The armature retainer acts as an intermediary component between the armature and valve needle. It includes a constriction surface that forms a fluid channel with the pole piece, creating a hydraulic restriction that mediates the force transmission. This intermediary structure allows the system to maintain both speed and controllability by using fluid pressure as a controlling medium rather than direct mechanical coupling alone.
Solution Approach 2:
The invention introduces a hydraulic restriction through the fluid channel formed between the armature retainer constriction surface and pole piece constriction surface. This hydraulic element creates a damping force that controls the valve needle's motion, allowing precise control of fluid injection amount while maintaining rapid response. The fluid pressure in the channel serves as a controllable parameter to balance speed and precision.
2Ease of operation
If the fluid channel is restricted to control fluid velocity, then the controllability of injection is improved, but the fluid flow resistance increases
Solution Approach 1:
The fluid channel's cross-sectional area is made variable through the axial displacement of the armature retainer. As the armature retainer moves axially, the distance between its constriction surface and the pole piece constriction surface changes, dynamically adjusting the hydraulic restriction. This dynamic adjustment allows the system to optimize between flow resistance and velocity control depending on the operational phase.
Solution Approach 2:
The invention changes the physical parameter of the fluid channel (its cross-sectional area) by displacing the armature retainer axially. This parameter change modifies the hydraulic restriction level, enabling control of fluid velocity while managing flow resistance. The constriction surfaces are designed with specific geometries to achieve the desired parameter transformation.
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 solution enhances controllability of fluid injection, maintaining efficient operation by reducing fluid velocity and variability, especially during the opening phase, thereby improving the injector's performance and reducing unwanted emissions.
Implementation Method 1
The injector (1) further comprises an electromagnetic actuator assembly (19), which is operable to exert a force for influencing a position of the valve needle (7)
Implementation Method 2
A hydraulically effective restriction is preferably formed between the armature retainer constriction surface (17) and the pole piece constriction surface (25)... The hydraulically effective restriction in particular effects a first damping force which is exerted on the valve needle (7)
Data Source
AI summary
An injector for injecting fluid with a valve assembly including a valve body and a valve needle, the needle including an armature retainer and being operable to prevent and to enable injection of fluid, and with an electromagnetic actuator assembly, operable to exert a force for influencing a position of the valve needle, including a pole piece and an armature. The pole piece is positionally fixed with the valve body. The armature is operable to be axially displaced relative to the pole piece and to take along the armature retainer when being displaced towards the pole piece. A fluid channel is defined by the armature retainer constriction surface and the pole piece constriction surface. A hydraulic diameter of the fluid channel is at least twice at large when the valve needle is in a closing position compared to the hydraulic diameter at a maximum displacement away from the closing position.