Fuel Injector Control Valve Segmentation for Leakage Reduction
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Solution Overview
Problem
In diesel fuel injectors, the existing 3-way valve design leads to energy losses and leakage during the needle opening phase due to direct pressurized fuel entering the return circuit via the second throttle, which slows down the needle lift and generates energy losses.
Innovation Solution
A fuel injector with a control valve assembly featuring a 3-way valve that controls the flow through a first throttle and a second throttle, where the valve plate is annular and movable, allowing the control chamber to be divided into compartments to prevent direct leakage by ensuring fuel flow through the first throttle only during filling and through both throttles during draining, utilizing a spring to manage the needle's position and prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If pressurised fuel flows through both the first throttle and second throttle during needle opening, then the control chamber drains faster enabling smoother needle lift, but direct leakage occurs from the second throttle to the return circuit via the first throttle causing energy losses
Solution Approach 1:
The control chamber is segmented into two separate compartments by the movable plate: a first compartment for filling operations and a second compartment for draining operations. This segmentation prevents direct leakage between the second throttle and return circuit while maintaining independent control over fuel flow paths, thus eliminating energy losses during needle opening phase.
Solution Approach 2:
A movable plate is introduced that can dynamically shift position based on operational phase. During filling, the plate allows flow through the first throttle; during draining, it redirects flow to prevent direct leakage. This dynamic reconfiguration optimizes both needle lift speed and energy efficiency by adapting the flow path to the current operational requirement.
2Productivity
If the 3-way valve directs fuel through the second throttle during needle opening, then asymmetric injection profile is achieved, but direct leakage to return circuit slows down needle opening and generates energy losses
Solution Approach 1:
The control chamber is divided into two compartments by a movable plate, separating the filling path (through first throttle) from the draining path (through second throttle). This prevents direct leakage during draining operations while maintaining the asymmetric injection profile, thus achieving both injection efficiency and acceptable needle opening timing.
Solution Approach 2:
The movable plate acts as an intermediary element that controls and directs fuel flow between compartments. During draining, it ensures fuel flows through the second throttle without direct leakage to the return circuit, thereby maintaining injection efficiency without sacrificing needle opening speed.
3Ease of operation
If the control chamber drains through both first and second throttles during injection phase, then smoother needle lift is achieved, but direct leakage occurs causing energy losses
Solution Approach 1:
The control chamber is segmented into two compartments by a movable plate, with the first compartment handling filling operations and the second compartment handling draining operations. This segmentation allows smooth needle lift during draining through the second throttle while preventing direct leakage to the return circuit, thus maintaining ease of operation without energy losses.
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 enables asymmetric injection profiles without incurring leakage penalties, maintaining similar injection quantities while reducing energy losses and preventing direct leakage during the injection phase, resulting in efficient needle lift and reduced energy consumption.
Implementation Method 1
a spring compressed between said needle shoulder and the under face of said annular plate
Implementation Method 2
pressurised fuel fills the control chamber by flowing through the first throttle and the second throttle
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A fuel injector (10) comprising a control valve assembly (12) arranged between an actuator assembly (14) and a nozzle assembly (16), wherein a 3-way valve controls the flow for filling or draining a control chamber through a first throttle and through a second throttle for enabling or preventing fuel injection, said second throttle being a through orifice provided in a plate arranged in said control chamber.