Fuel Injector Nozzle Body Throttle Stability Design
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Solution Overview
Problem
Fuel injectors in internal combustion engines face performance variability due to changing fuel pressure, which affects the nozzle body's throttle dimensions, leading to inconsistent fuel pressure drops and operating issues.
Innovation Solution
A nozzle body design with an inter-chambers portion and a cylindrical tubular wall that maintains constant throttle dimensions by balancing radial forces from pressurized fuel, using either an integral tubular wall or a fixed sleeve, and a collar with specific edge configurations to guide the valve needle and induce a consistent fuel pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the throttle is formed as an annular clearance between the nozzle body and collar, then the structure is simple, but the throttle dimensions vary with fuel pressure causing performance inconsistency
Solution Approach 1:
The patent applies the counterweight principle by introducing a cylindrical tubular wall that protrudes into the upstream chamber. This tubular wall is subjected to radial forces from pressurized fuel that balance the radial forces acting on the throttle clearance, thereby compensating for pressure-induced dimensional changes and maintaining stable throttle dimensions across varying fuel pressures.
Solution Approach 2:
The patent introduces a new spatial dimension by adding the cylindrical tubular wall extending axially into the upstream chamber. This additional structural element creates a new force balance dimension that counteracts the pressure-induced radial deformation of the throttle clearance, stabilizing the throttle dimensions without complicating the basic annular clearance structure.
2Reliability
If the nozzle body is rigid to maintain throttle dimensions, then throttle stability is improved, but the structure becomes more complex requiring additional components
Solution Approach 1:
The patent applies the self-service principle by designing the cylindrical tubular wall to automatically balance the radial forces through the natural pressure distribution of the fuel system. The tubular wall itself serves as the balancing mechanism, utilizing the fuel pressure to generate counteracting forces without requiring external control systems or additional active components.
Solution Approach 2:
The patent merges the force-balancing function with the existing nozzle body structure by integrating the cylindrical tubular wall as part of the nozzle body or as a fixed sleeve within it. This combination allows the throttle stabilization function to be achieved without adding separate independent components, thereby limiting the increase in device complexity.
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 ensures a constant throttle clearance, regardless of fuel pressure variations, maintaining consistent fuel pressure drops and improving injector performance by preventing throttle dimension changes.
Implementation Method 1
The pressurized fuel induces opposed radial forces on the outer and inner cylindrical faces of the tubular wall so that advantageously, the throttle dimensions remains constant
Implementation Method 2
The inter-chambers portion has a cylindrical tubular wall axially protruding in the upstream chamber and being adapted to cooperate, in use, with the valve needle to define a throttle inducing a fuel pressure drop
Data Source
AI summary
A nozzle body (16) of a fuel injector (10) has an inner space extending along a main axis (A) and adapted to receive a slidably arranged valve needle (14), the inner space being divided in an upstream cylindrical chamber (38) and, a downstream cylindrical chamber (40). The nozzle body (16) is further provided with an inter-chambers (42) portion having a cylindrical tubular wall (44) axially protruding in the upstream chamber (38) and being adapted to cooperate, in use, with the valve needle (14) to define a throttle (28) inducing a fuel pressure drop.