Alternative-Fuel Injector Using Control Fluid for Sealing and Lubrication
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Solution Overview
Problem
Existing injectors for large engines using alternative fuels face challenges with fuel toxicity, flammability, and leakage, necessitating a control fluid different from the fuel, which complicates the injector design and increases size and complexity.
Innovation Solution
An injector design that uses a control fluid with higher viscosity than the fuel, separate from the fuel, to control the opening and closing of the needle, with a lubrication system that utilizes spillover control fluid to lubricate the needle guide, reducing complexity and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a control fluid different from the fuel is used to operate the injector, then safety is improved by avoiding toxicity and flammability risks, but device complexity increases due to additional sealing oil lines and lubrication systems
Solution Approach 1:
The patent merges the lubrication function and sealing function into a single control fluid system. The control fluid serves dual purposes: it acts as both the control medium for the injector and the lubricant for the needle guide, eliminating the need for separate sealing oil lines and reducing overall system complexity while maintaining safety benefits
Solution Approach 2:
The control fluid is designed to perform multiple functions simultaneously: it controls the injector operation, lubricates the needle guide, and provides sealing against fuel leakage. This multi-functionality reduces the number of separate systems needed and simplifies the overall injector design
2Reliability
If the injector needle guide is lubricated using a separate sealing oil line, then lubrication is ensured, but the injector size increases and manufacturing complexity increases
Solution Approach 1:
The patent combines the lubrication function with the control fluid system, eliminating the need for separate sealing oil lines. The control fluid flows through the needle guide to provide lubrication while maintaining compact injector dimensions and simplifying manufacturing
3Reliability
If the pressure in the intermediate groove is kept higher than the injection chamber pressure, then fuel leakage is prevented, but device complexity increases due to additional pressure control mechanisms
Solution Approach 1:
The patent extracts the pressure control function from the fuel system and integrates it into the control fluid system. By maintaining higher pressure in the control fluid supply, the system automatically ensures proper sealing in the intermediate groove without requiring additional complex pressure control mechanisms
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 effective lubrication and sealing while maintaining a compact structure, simplifying manufacturing and reducing the forces required for sealing, suitable for common-rail injectors in four-stroke engines using methanol, ammonia, or gas.
Implementation Method 1
a control fluid different from the fuel and having a substantially higher viscosity than the viscosity of the fuel is used
Implementation Method 2
a lubrication system that utilizes spillover control fluid to lubricate the needle guide
Implementation Method 3
The fluid pressure in the injection chamber acts in the direction of opening the injection needle. The fluid pressure in the control chamber generates a hydraulic force that acts in the direction of closing the injection needle
Implementation Method 4
which generally also acts as a sealing element against fuel leakage through the needle guide
Data Source
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AI summary
An injector for alternative fuels, comprising: - a body (14) including an injection chamber (16) provided with a valve seat (20) and a needle guide surface (34), - a fuel supply line (22) that supplies pressurized fuel to the injection chamber (16), - an injection needle (30) having a sliding surface (58) that cooperates with the needle guide surface (34) to guide the movement of the injection needle (30) between a closed position and an open position and vice versa, wherein an annular gap (66) is formed between the sliding surface (58) of the injection needle (30) and the needle guide surface (34), - a control piston (70) having a first end (72) facing a control chamber (18), wherein a lubrication line (76) places the annular gap (66) in fluid communication with the control chamber (18), so that during operation the annular gap (66) is filled with control fluid.