Gaseous Fuel Injector Sealing for High-Flow Needle Control
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Solution Overview
Problem
Existing fuel injectors struggle to deliver high flow rates of gaseous fuels like hydrogen efficiently due to varying injection pressures, leading to increased reaction forces that exceed the magnetic force required to lift the valve needle, and result in leakage and wear issues.
Innovation Solution
A fuel injector design with separate fluid supply networks for control fluid and gaseous fuel, incorporating sealant chambers connected to the control fluid network at higher pressure to inhibit leakage and lubricate interfaces, maintaining a pressure difference to facilitate easy valve needle lifting and reduce wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large valve seat is used to provide sufficient flow rate for gaseous fuel, then the flow rate is improved, but the reaction forces against the return spring increase making valve needle lifting difficult
Solution Approach 1:
The patent divides the fluid control into separate systems: a first fluid supply network for control fluid and a second fluid supply network for gaseous fuel. This segmentation allows independent optimization of control force (via control fluid pressure) and fuel flow rate (via valve seat size), resolving the contradiction between large valve seat requirements for high flow and the resulting excessive reaction forces.
Solution Approach 2:
The control fluid acts as an intermediary that mediates the valve needle movement. Instead of relying solely on the return spring to overcome reaction forces, the control fluid pressure provides an additional force to assist in lifting the valve needle, enabling the use of larger valve seats for higher flow rates without being limited by excessive reaction forces.
2Reliability
If separate fluid supply networks are used for control fluid and gaseous fuel, then leakage is inhibited, but device complexity increases
Solution Approach 1:
The patent implements separate fluid supply networks for control fluid and gaseous fuel, segmenting the fluid paths to prevent cross-contamination and leakage. This segmentation ensures that control fluid and gaseous fuel remain isolated, improving reliability by eliminating leakage risks between the two fluid systems.
Solution Approach 2:
The control fluid serves multiple functions: it controls valve needle movement through the needle control valve, and it provides sealing pressure in the sealant chambers to prevent gaseous fuel leakage. This multi-functionality reduces the need for additional dedicated sealing mechanisms, thereby limiting the increase in device complexity while achieving effective leakage prevention.
3Reliability
If control fluid pressure is increased to inhibit leakage, then leakage is reduced, but the force required to lift the valve needle increases
Solution Approach 1:
The patent segments the control fluid pressure application into two distinct functions: high pressure in the sealant chambers for leakage inhibition, and controlled pressure in the control chamber for valve needle actuation. This segmentation allows the system to maintain high control fluid pressure for sealing without excessively increasing the force required for valve needle lifting, as the needle control valve regulates the pressure specifically where it acts on the valve needle.
Solution Approach 2:
The control fluid pressure is applied with different local qualities: in the sealant chambers, high pressure is maintained for leakage prevention, while in the control chamber, the pressure is regulated by the needle control valve to provide appropriate lifting force. This local differentiation of pressure quality allows simultaneous achievement of leakage inhibition and manageable valve needle lifting forces.
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 efficient delivery of gaseous fuels across varying pressures without leakage, maintaining accurate control and reducing wear on valve components.
Implementation Method 1
each sealant chamber is supplied with the control fluid from the first fluid supply network at a higher pressure than the supply of fuel in the second fluid supply network, thereby substantially inhibiting leakage from the second fluid supply network via the respective leakage path
Implementation Method 2
The sealant chamber is configured such that a lubricating flow of control fluid leaks, in use, from the sealant chamber into the delivery chamber
Data Source
AI summary
A fuel injector of a fuel injection system for delivering gaseous fuel to an internal combustion engine comprises: an injector nozzle having a valve needle that is movable within a bore of the injector nozzle; a needle control valve; a first fluid supply network for conveying the control fluid from a first injector inlet to an inlet of the needle control valve; a second fluid supply network for conveying the gaseous fuel from a second injector inlet to a delivery chamber, defined around the valve needle in the bore of the injector nozzle, for injection into the engine; and one or more sealant chambers for sealing respective leakage paths of the second fluid supply network, each leakage path extending between respective adjacent bodies of the fuel injector and the respective sealant chamber being defined at interfacing surfaces of those bodies to enclose that leakage path.