Fuel Injector Armature Cavity Pressure Reduction
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Solution Overview
Problem
Common rail fuel injectors experience 'injector bounce' due to quick closure of the control valve, leading to delays in injection termination and additional fuel injection, which reduces engine efficiency and causes unstable operation.
Innovation Solution
An insert with a venturi structure is used within the armature cavity to reduce pressure fluctuations by creating a low-pressure environment through the flow of low-pressure coolant, which helps in dampening the oscillations of the armature and preventing unwanted fuel injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the control valve closes quickly to improve injection termination, then injection precision is improved, but injector bounce occurs causing additional fuel injection and unstable engine operation
Solution Approach 1:
A damping element is positioned within the armature cavity to provide cushioning before the armature can bounce off the seat. This pre-positioned damping mechanism absorbs the rebound energy and prevents injector bounce, thereby maintaining reliable engine operation while preserving quick valve closure for precise injection termination.
2Loss of time
If the control valve closes quickly to terminate injection, then injection timing precision is improved, but pressure oscillations in the armature cavity cause delayed injection termination
Solution Approach 1:
The damping element is pre-positioned in the armature cavity to cushion pressure oscillations before they can cause armature bounce and injection timing delays. This absorbs the harmful pressure fluctuations and maintains stable injection timing.
Solution Approach 2:
The damping element acts as an intermediary between the control valve and the armature, absorbing pressure oscillations and preventing them from transmitting to the armature. This mediator prevents the chain reaction that leads to delayed injection termination.
3Reliability
If an insert with venturi structure is added to reduce armature cavity pressure, then injector bounce is reduced, but device complexity increases
Solution Approach 1:
The insert is designed to perform multiple functions: it creates the venturi effect to reduce armature cavity pressure, provides structural support within the cavity, and guides the armature movement. By combining multiple functions in a single component, the overall device complexity is minimized while achieving reliable injection consistency.
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 solution effectively reduces pressure oscillations within the armature cavity, minimizing injector bounce and ensuring smoother and more efficient engine operation by maintaining a consistent low-pressure environment, thereby preventing premature opening of the needle element and reducing fuel injection delays.
Implementation Method 1
The insert may have at least a portion of a venturi formed therein that is configured to reduce a pressure of the armature cavity
Implementation Method 2
a first passage formed at least partially within the lower surface and having an effuser portion, a neck portion, and a diffuser portion
Data Source
AI summary
A fuel injector for an engine is disclosed. The fuel injector may have a fuel nozzle with at least one injection orifice, and a needle element movable within the fuel nozzle between a first position at which the needle element inhibits fuel flow and a second position at which fuel flow is substantially uninhibited. The fuel injector may also have a control chamber located at a base end of the needle element, a body, and a control valve disposed within the body and movable to selectively drain the control chamber, thereby causing the needle element to move between the first and second positions. The fuel injector may further have an armature disposed within an armature cavity of the body and selectively energized to move the control valve, and a pressure reducer disposed within the body and configured to reduce a pressure of the armature cavity.