Diesel Fuel Injector Return Channel Widened Zone
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Solution Overview
Problem
Diesel fuel injectors experience material fatigue due to high, cyclic, and concentrated mechanical stresses at the exit of the discharge channel, primarily caused by the rapid operation of the solenoid valve at frequencies over 100 Hz, which affects the durability of the injector body.
Innovation Solution
A diesel fuel injector design featuring a return channel with a widened zone that includes a cylindrical section, a conical section, and a toroidal connection surface, where the discharge channel opens, reducing mechanical stresses by distributing the pressure and cyclic loads more evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the solenoid valve operates at high frequency (over 100 Hz) to control fuel pressure, then the fuel injection control precision is improved, but high cyclic mechanical stresses are generated at the discharge channel exit causing material fatigue
Solution Approach 1:
A widened zone is introduced as an intermediary structure between the discharge channel and the return channel. This zone acts as a stress-distributing mediator that receives the high-pressure fuel flow from the discharge channel and gradually transitions it into the return channel, thereby reducing the concentrated mechanical stresses at the discharge channel exit while maintaining the high-frequency valve operation capability
Solution Approach 2:
The return channel is designed with a localized widened zone at the discharge channel exit, while the rest of the return channel maintains its original dimensions. This local modification concentrates the stress-relief function in the critical area where high cyclic stresses occur, without affecting the overall fuel return capability or increasing the complexity of the entire system
2Volume of moving object
If the discharge channel section is kept small to maintain compact injector design, then the device size is reduced, but the mechanical stresses become highly concentrated causing durability issues
Solution Approach 1:
The return channel is designed with a localized widened zone at the discharge channel exit, while the rest of the return channel maintains its original dimensions. This local modification concentrates the stress-relief function in the critical area where high cyclic stresses occur, without affecting the overall fuel return capability or increasing the complexity of the entire system
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 significantly reduces material fatigue by mitigating the mechanical stresses associated with high-pressure fuel passage and valve cycling, enhancing the durability and longevity of the injector.
Implementation Method 1
The solenoid valve manages the pressure in the control chamber and thereby the difference in pressure between the upstream and downstream of the needle
Implementation Method 2
the cylindrical section of the enlarged zone flares out into a conical section into which the discharge channel also opens... the mechanical stresses linked to the passage of the fuel C under pressure and to the cycles of the valve are reduced
Data Source
Figure 1~3
AI summary
A diesel fuel injector (10) has a body (12) through which pressurized fuel (C) flows between an inlet and a needle-controlled injection nozzle. The needle moves axially under the influence of the pressure difference between a control chamber (16) arranged upstream of the needle and the downstream injection nozzle. The injector (10) further includes a pilot-operated valve (14) that controls the pressure in the control chamber (16) by opening or closing a discharge channel (18) extending from the control chamber (16) and opening into a larger-section, low-pressure cylindrical return channel (20). The return channel (20) has an enlarged area (22) into which the discharge channel (18) opens, thereby reducing the mechanical stresses associated with the passage of pressurized fuel (C) and the cycles of the valve (14).