Injector Closing Spring Layout for High Combustion Pressure Sealing
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Solution Overview
Problem
Existing injectors for internal combustion engines face challenges in maintaining the nozzle needle in a closed position against high combustion chamber pressures, particularly when injecting alternative fuels like ammonia or alcohols, without risking damage from combustion chamber gases.
Innovation Solution
The injector design incorporates a dual closing spring system, where a second closing spring in a separate spring chamber generates a high closing force on the nozzle needle, and a guide sleeve seals the control chamber, ensuring the nozzle needle remains closed even under high combustion chamber pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a single closing spring is used in the control chamber, then the device complexity is low, but the closing force is insufficient to counteract high combustion chamber pressures
Solution Approach 1:
The closing spring system is segmented into two independent springs: a first closing spring arranged in the control chamber and a second closing spring arranged in a separate spring chamber. This segmentation allows each spring to contribute to the total closing force while maintaining structural organization and ease of assembly. The two springs work together to generate sufficient closing force to counteract combustion chamber pressures up to 350 bar.
Solution Approach 2:
The second closing spring is placed in a separate spring chamber that is axially adjacent to the control chamber, utilizing the longitudinal dimension of the injector body. This spatial arrangement allows the second spring to exert force on the nozzle needle without interfering with the control chamber's hydraulic function, effectively adding another dimension to the force generation system.
2Reliability
If the control chamber is not sealed, then the device complexity is low, but combustion chamber gases can penetrate and damage the injector
Solution Approach 1:
A guide sleeve is introduced as an intermediary sealing element between the control chamber and the combustion chamber environment. The guide sleeve features a sealing edge that contacts the nozzle needle, creating a reliable seal that prevents combustion chamber gases from penetrating into the control chamber while allowing the nozzle needle to move freely during injection operations.
Solution Approach 2:
The guide sleeve acts as a flexible sealing structure that can accommodate the movement of the nozzle needle while maintaining the seal. The sealing edge of the guide sleeve creates a dynamic seal that remains effective throughout the opening and closing cycles of the nozzle needle, protecting the control chamber from combustion gases.
3Device complexity
If the second closing spring is placed inside the control chamber, then the device complexity is low, but the control chamber volume is reduced and spring design is constrained
Solution Approach 1:
The spring system is segmented into two separate locations: the first closing spring in the control chamber and the second closing spring in a dedicated spring chamber. This segmentation provides ample space for the second spring to be designed with optimal dimensions, shape, and geometry without constraining the control chamber volume or compromising the hydraulic control function.
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
This design effectively maintains the nozzle needle in the closed position, protecting the injector from combustion chamber gases, even at pressures up to 350 bar, while allowing precise control over injection.
Implementation Method 1
the nozzle needle, viewed in the direction of its longitudinal axis, is guided radially in a guide section of the injector housing between the pressure chamber for the working medium and the control chamber for the control medium; that the pressure of the control medium in the control chamber acts on a control surface arranged perpendicular to the longitudinal axis of the nozzle needle
Implementation Method 2
A second closing spring is arranged in a spring chamber separate from the low-pressure area. This second closing spring is designed to exert a greater force on the nozzle needle towards its closed position than the first closing spring
Implementation Method 3
the guide sleeve is subjected to a force by a first closing spring against a component that delimits the control chamber
Implementation Method 4
the pressure of the control medium in the control chamber acts on a control surface arranged perpendicular to the longitudinal axis of the nozzle needle
Implementation Method 5
the nozzle needle, in its closed position, rests against a wall section of the pressure chamber, forming a sealing seat
Data Source
Figure 1
Figure 2
AI summary
The invention relates to an injector (10) for discharging a pressurized working medium into a combustion chamber (1) of an internal combustion engine (2), comprising: - an injector housing (22), in which a nozzle needle (34) is longitudinally movably disposed between a closed position, in which the nozzle needle closes at least one inlet opening (26) for the working medium into the combustion chamber (1), and an open position, in which the nozzle needle leaves the at least one inlet opening (26) open; - a pressure chamber (28) for the working medium, the pressure chamber being located in the injector housing (22); and - a control chamber (46), which is located in the injector housing (22) and which can be filled with a pressurized control medium different from the working medium.