Common-Rail Injector Stroke Limiting Mechanism
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Solution Overview
Problem
Existing common rail injectors with long nozzle needles lack a precise mechanism to limit the maximum opening stroke, leading to inefficient assembly and optimization of components, as the device for setting the maximum lift is not separated from the control chamber.
Innovation Solution
A common rail injector design where the nozzle needle has a second element that is fixed in the injector housing, allowing for a separate device to limit the maximum opening stroke, with a passage for fuel flow even when fully open, enabling the control chamber to be positioned away from the injection opening and the stroke limiting device to be close to it, optimizing component assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the control chamber and stroke limiting device are integrated in existing common-rail injectors, then the structure is compact, but the adjustment of maximum opening stroke is difficult and component optimization is limited
Solution Approach 1:
The injector is divided into functionally independent modules: a control chamber module (with control chamber, nozzle body, injection opening) and a stroke limiting device module (with first element, second element, axial gap). This segmentation allows each module to be optimized independently while maintaining compact overall structure through modular assembly.
Solution Approach 2:
The stroke limiting function is extracted from the control chamber structure. The second element is completely penetrated by the nozzle needle and positioned independently, with the axial gap between first and second elements providing the stroke limit adjustment capability separate from the control chamber geometry.
2Ease of manufacture
If the second element is positioned close to the injection opening, then assembly is simplified, but fuel flow passage design becomes more complex
Solution Approach 1:
The second element acts as an intermediary component with fuel passages that bridge the high-pressure chamber and the injection opening area. It completely penetrates the nozzle needle, providing both mechanical function (stroke limiting) and fluid transport function, thereby simplifying assembly while managing the passage design complexity through integrated functionality.
3Manufacturing precision
If the nozzle needle is made long for better spray control, then injection performance improves, but the maximum stroke becomes harder to limit precisely
Solution Approach 1:
The mechanical stroke limiting mechanism replaces direct geometric constraints on the long nozzle needle. Instead of relying on the needle length alone, the axial gap between the first element (fixed to housing) and second element (penetrating the needle) provides a precise, adjustable mechanical stop that limits the maximum opening stroke regardless of needle length, enabling precise spray control with long needles.
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 allows for precise control of the nozzle needle's opening stroke, enhancing fuel flow and reducing wear, while enabling a preassembled assembly of components, thus improving the injector's efficiency and assembly process.
Implementation Method 1
the second element has at least one passage for fuel between the two bore sections. This passage is therefore of particular importance, as it ensures that even with the nozzle needle fully open, where the second element rests against the front face of the other housing element, fuel can flow into the area of at least one injection opening.
Data Source
Figure 1
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Figure 3~4
AI summary
The invention relates to a common rail injector (10) comprising an injector housing (11) in which a nozzle needle (25) - arranged such that it can move in strokes - is arranged in a high-pressure chamber (18) for releasing or blocking at least one injection opening (15) formed in the injector housing (11), wherein an end region of the nozzle needle (25) facing away from the at least one injection opening (15) dips into an element (36) to form a control space (38), and wherein the nozzle needle (25) cooperates with a device (50) for limiting the maximum opening stroke of the nozzle needle (25), which device preferably has a first preferably sleeve-like element (33), which is arranged axially fixed on the nozzle needle (25) and is applied with force by a reset spring (34) in the closing direction of the nozzle needle (25), and which device has a second, preferably likewise sleeve-like element (35; 35a) which radially surrounds the nozzle needle (25) and is arranged axially fixed in the injector housing (11) on the side facing away from the first element (33).