Valve Assembly Fuel Injection System Inversion Dynamics
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Solution Overview
Problem
Conventional fuel injection systems face issues where a failure to provide a control signal to the inlet metering valve can lead to either cessation of fuel delivery or continuous high-pressure fuel delivery, resulting in engine stoppage or overpressurization, respectively, due to the use of normally-closed or normally-open valves, which increase system complexity with the need for pressure-limiting valves.
Innovation Solution
A valve assembly with a moveable valve element that allows fluid flow at a low rate when no control signal is present, transitioning to a closed position to prevent flow, and fully opening when a high signal is applied, reducing the risk of overpressurization by controlling fuel flow rates from zero to maximum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a normally-closed inlet metering valve is used, then fuel delivery is prevented in case of control signal failure, but the engine stops and fuel rail cannot be pressurized
Solution Approach 1:
The patent inverts the conventional normally-closed valve design to a normally-open valve with a biasing spring that maintains the valve in an open position. The valve closes only when an active control signal is applied. This inversion ensures that in case of control signal failure, the valve remains open and fuel delivery continues, allowing the engine to operate while preventing overpressurization through the variable flow capability.
2Productivity
If a normally-open inlet metering valve is used, then engine operation is maintained in case of control signal failure, but the fuel rail overpressurizes
Solution Approach 1:
The patent implements a dynamic valve design where the valve element can assume multiple positions (fully open, partially open, fully closed) rather than just binary open/closed states. The biasing spring provides a restoring force that allows the valve to return to a controlled open position when the control signal is removed, enabling the system to maintain engine operation while regulating fuel flow to prevent overpressurization of the fuel rail.
3Ease of operation
If binary open/closed valve positions are used, then simple control is achieved, but precise fuel pressure control is insufficient
Solution Approach 1:
The patent employs a valve element capable of partial opening positions between fully closed and fully open states. The biasing spring mechanism allows the valve to settle at intermediate positions based on the control signal magnitude, enabling precise modulation of fuel flow. This partial action capability provides continuous fuel pressure control while maintaining relatively simple actuator design, as the spring assists in achieving stable intermediate positions.
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
Enables engine operation without overpressurization by allowing restricted fuel flow when no control signal is present, while allowing precise control of fuel pressure through variable flow rates, eliminating the need for pressure-limiting valves and simplifying the fuel injection system design.
Implementation Method 1
the valve element is biased to return to a rest position when the control signal is absent
Data Source
AI summary
A valve assembly suitable for use as an inlet metering valve of a fuel injection system, comprising inlet means (126, 128), outlet means (136), and a valve element (104) arranged to control fluid flow between the inlet means and the outlet means. The valve element is moveable in response to an applied control signal to a closed position (B) and to a fully-open position (D), and is biased to return to a rest position (A) when the control signal is absent. When the valve element is in the rest position, fluid flow is permitted at a relatively low rate. When the valve element is in the closed position, fluid flow is prevented. When the valve element is in the fully-open position, fluid flow is permitted at a high rate. A method for controlling fuel pressure in a fuel injection system of an is also disclosed. The valve provides a predetermined amount of fuel bypass so that the engine continues to operate in the event of a system failure (signal interruption) in order to prevent engine stopping.