Fuel Injector High-Pressure Chamber Radial Compression
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Solution Overview
Problem
Current fuel injectors face material stress and risk of damage due to increasing system pressures, as the existing design with small wall thickness and limited installation space cannot effectively manage tensile stresses without using high-strength materials, which are costly and undesirable.
Innovation Solution
The fuel injector design features a high-pressure chamber delimited by two elements, where a radially outer element exerts a compressive force on a sleeve-shaped inner element, counteracting tensile stresses and maintaining structural integrity without requiring stronger materials, by forming a press fit and ensuring radial compressive stress across the circumference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the system pressure is increased to higher values (up to 3000 bar), then the injection performance is improved, but the tensile stress on the injector housing material increases causing risk of cracks or damage
Solution Approach 1:
The patent changes the stress state parameter of the inner element from purely tensile to a combination of compressive and tensile stresses. By introducing the outer element that applies radial compressive force, the stress distribution in the inner element is fundamentally altered, allowing the material to withstand higher system pressures without exceeding its tensile strength limit.
Solution Approach 2:
The outer element acts as a counterweight structure that applies a compressive force opposite to the tensile stress generated by the system pressure. This compressive pre-stress counteracts the harmful tensile stress, effectively reducing the net tensile stress on the inner element to levels that prevent cracking and damage.
2Adaptability or versatility
If additional components are arranged within the high-pressure chamber, then the functional capability is improved, but the wall thickness of the injector housing must be reduced due to limited installation space
Solution Approach 1:
The patent implements a nested structure where the inner element containing the high-pressure chamber is placed inside the outer element. This nested arrangement allows additional functional components to be accommodated within the inner element's cavity while the outer element provides the necessary structural strength and stress compensation, effectively decoupling the functional requirements from the structural thickness requirements.
3Strength
If the wall thickness of the injector housing is increased to manage tensile stresses, then the structural strength is improved, but the outer diameter increases beyond the limited installation space
Solution Approach 1:
The patent applies local quality by concentrating the stress-management function in the outer element that surrounds the inner element. Instead of uniformly increasing the wall thickness of the entire injector housing, the reinforced structure is localized to the outer element that directly contacts and compresses the inner element, providing targeted strength where needed while maintaining compact overall dimensions.
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 compensates for tensile stresses within the inner element, enhancing mechanical strength and reliability, allowing for higher system pressures up to 3000 bar while maintaining the same internal and external dimensions, and ensuring functional reliability across varying temperatures.
Implementation Method 1
the second element is connected to form a radially acting compressive force on the first element with this. The compressive force causes compressive stresses to arise within the wall of the inner element on the side facing the high-pressure chamber, which opposes the tensile stresses caused as a result of the system pressure
Implementation Method 2
a press fit is formed between the outer diameter of the first element and the inner diameter of the second element
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a fuel injector (10) with an injector housing (11) which forms a high-pressure chamber (30) that can be connected to a high-pressure source (33) and in which an injection valve element (13) is arranged to be movable by stroke. According to the invention, the high-pressure chamber (30) is at least partially bounded by two elements (16; 16a; 16b, 17; 17a), an inner first, sleeve-shaped element (16; 16a; 16b) with a first recess (52; 52a) arranged in the first element (16; 16a; 16b) for forming the high-pressure chamber (30), and a second element (17; 17a) directly surrounding the first element (16; 16a; 16b) with a second recess (53; 53a), wherein the second recess (53; 53a) surrounds the first element (16; 16a; 16b) on its outer circumferential surface (51), and wherein the second element (17; 17a) exerts a radially acting pressure force on the first element (16; 16a; 16b) is connected with this.