Fuel Injector Cap Design for Seal Protection and Height Reduction
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Solution Overview
Problem
Conventional fuel injectors with side entry connections face installation challenges, particularly when an engine top cover is fitted, as the aperture seal can be damaged, and steepening the side inlet to ease installation reduces the height benefit.
Innovation Solution
A fuel injector design featuring a cap that fits over the trailing end of the injector body, creating a chamber for backleak fuel with a fitting that secures via a conical connection, preventing relative movement and avoiding direct threading, thus minimizing axial height and simplifying installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a side entry connection is used to reduce axial height, then the height of the assembly is reduced, but the aperture seal may be damaged when installing the engine top cover
Solution Approach 1:
The fuel injector assembly is divided into separate components: the injector body with axial threaded connection and the cap with side entry port. This segmentation allows the injector body to be installed first through the engine top cover aperture, preserving the seal, while the cap with side entry is attached afterward to provide reduced axial height for fuel delivery pipe connection.
2Ease of operation
If the side inlet is steepened to ease engine cover installation, then the aperture seal is less likely to be damaged, but the height reduction benefit is reduced
Solution Approach 1:
By separating the injector body from the cap assembly, the design eliminates the need to compromise the side inlet angle. The injector body maintains a gentle side inlet angle for easy engine cover installation, while the cap provides the necessary axial height reduction for fuel delivery pipe connection, resolving the trade-off between ease of installation and height reduction.
3Strength
If direct threading is used to secure the fitting to the injector body, then the connection is secure, but the manufacturing cost and assembly complexity increase
Solution Approach 1:
The connection system is segmented into the injector body with external threads and the cap with internal threads. This segmentation allows each component to be manufactured independently with standard threading, simplifying manufacturing and assembly while providing secure mechanical connection and sealing between the injector body and cap.
Data Source
Figure 1~2
AI summary
A fuel injector (10) has an injector body (12) having a leading end (16), a trailing end (20), a fuel inlet passage (30) and a backleak passage (22) and a fitting (14) that fits onto said injector body at a position remote from the leading end. A chamber (60) for receiving fuel from the backleak passage is defined between the injector body and the fitting.