Oval Contour Flow Restrictor for Common Rail Injector
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Solution Overview
Problem
In modular common rail fuel injection systems for large engines, the long lines between injectors result in a significant drop in injection pressure, leading to reduced injection rates and potential continuous injection issues due to wear in the flow limiter components, which can cause safety risks.
Innovation Solution
The flow limiter features a locking bolt with a high-pressure connection, a valve housing, a ball, and a spring, where the support seat has an oval contour to reduce contact pressure peaks, and a high-pressure bore with an elliptical or oval shape to maintain hydraulic connection and prevent continuous injection, while being compact and easy to manufacture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circular bearing surface with grooves or pockets is used to maintain hydraulic connection, then the bypass function is achieved, but the sharp-edged contour causes high wear and reduces service life
Solution Approach 1:
The bearing surface is designed with an oval contour instead of a circular one with sharp edges. This curved, rounded geometry reduces stress concentration and contact pressure peaks at the interface between the ball and bearing surface, thereby minimizing wear and extending the service life of the flow restrictor while maintaining the bypass function.
2Ease of operation
If the ball frequently contacts the bearing surface to open the hydraulic connection, then the bypass function operates, but repeated contact causes wear and potential malfunctions
Solution Approach 1:
The oval contour of the bearing surface distributes contact forces more evenly during repeated ball contacts, reducing localized wear and preventing malfunctions that would result from sharp-edged contact surfaces.
3Adaptability or versatility
If long high-pressure lines are used to connect injectors in large engines, then the modular system can be implemented, but injection pressure drops significantly reducing injection rate
Solution Approach 1:
The flow restrictor with oval bearing surface prevents wear-related malfunctions that could cause continuous injection, ensuring the modular system operates reliably throughout its service life without pressure loss from injector failures.
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 enhances the service life of the flow limiter, reduces wear-related malfunctions, and prevents continuous injection into the combustion chamber, ensuring safer and more reliable fuel injection by minimizing contact pressure peaks and maintaining a bypass function.
Implementation Method 1
The ball is acted upon by the spring in the direction of the bearing seat
Implementation Method 2
The oval contour reduces peak contact pressures between the ball and the mounting surface
Implementation Method 3
When the ball rests against the bearing seat, it opens a hydraulic connection from the high-pressure port through the axial bore; when it rests against the valve seat, it closes the hydraulic connection
Data Source
Figure 1
Figure 2a~2b
AI summary
The invention relates to a flow restrictor (16) for an injector of a common rail fuel injection system. The flow restrictor (16) has a closure bolt (5) with a high-pressure connection (20), a valve housing (24), a ball (15), and a spring (17). A support seat (28) is formed on the closure bolt (5), and a valve seat is formed on the valve housing (24). The ball (15) is arranged in an axial bore (11a) formed in the valve housing (24) and is acted upon by the spring (17) in the direction of the support seat (28). Upon contacting the support seat (28), the ball (15) releases a hydraulic connection of the high-pressure connection (20) through the axial bore (11a), and upon contacting the valve seat (18), the ball blocks the hydraulic connection. The support seat (28) has an oval contour.