Locating Pin Design for Fuel Injector Alignment and Stress Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fuel injectors experience metal fatigue and failure due to the immense forces generated during the activation of solenoids, high-pressure mixing, and rapid combustion, leading to reduced performance or failure.
Innovation Solution
A fuel injector assembly design featuring end caps and a control valve body with strategically positioned locating pins and bores that distribute stress and maintain alignment, even in the event of pin failure, using elongated pins with counter bores to absorb edge stress and allow for rotation, thereby increasing durability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional locating pins are used to connect end caps to control valve body, then assembly alignment is maintained, but metal fatigue and pin breakage occur due to immense forces from solenoid activation, high-pressure mixing, and rapid combustion
Solution Approach 1:
The patent implements a two-bore design where the second bore (counterbore) with larger diameter than the first bore creates a stress-distributing structure. The locating pin extends into both bores, with the second bore proximate to the mating surface providing additional support and stress distribution. This beforehand cushioning structure prevents pin breakage by distributing the immense forces from solenoid activation, high-pressure mixing, and rapid combustion across a larger area, reducing stress concentration at any single point.
Solution Approach 2:
The patent applies local quality by creating different bore diameters within the same locating hole structure. The first bore has a smaller diameter for precise pin fitment and alignment, while the second bore has a larger diameter to distribute stress. This local differentiation allows the locating pin structure to simultaneously maintain alignment precision and resist metal fatigue from extreme forces.
2Manufacturing precision
If locating pins are made longer to improve alignment stability, then alignment precision is improved, but the pins become more susceptible to bending and failure under extreme combustion forces
Solution Approach 1:
The two-bore structure provides beforehand cushioning by creating a stepped geometry where the pin is supported at two different depths. The first bore provides initial support for alignment, while the second bore (counterbore) proximate to the mating surface provides additional support deeper in the material. This distributed support system maintains alignment precision without requiring excessive pin length that would increase bending susceptibility.
Solution Approach 2:
The patent transitions from a single-depth pin insertion to a two-level insertion system with bores at different depths along the longitudinal axis. The first bore is remote from the mating surface while the second bore is proximate to it. This dimensional change in the insertion structure allows the pin to be supported at multiple levels, improving alignment while distributing stress to prevent bending and failure.
3Ease of manufacture
If conventional single-bore locating holes are used, then manufacturing is simple, but stress concentration occurs at the pin insertion point leading to metal fatigue
Solution Approach 1:
The two-bore design implements beforehand cushioning by creating a stress-distributing geometry before the pin is subjected to extreme forces. The second bore with larger diameter, positioned proximate to the mating surface, provides a stress-relief zone that prevents stress concentration at the pin insertion point. This structure is manufactured using standard counterboring operations, maintaining ease of manufacture while dramatically improving resistance to metal fatigue.
Solution Approach 2:
The patent applies local quality by differentiating the bore diameters within the locating hole structure. The first bore has a smaller diameter for precise pin fitment, while the second bore has a larger diameter specifically at the stress-prone region near the mating surface. This local structural differentiation maintains manufacturing simplicity through standard machining operations while preventing stress concentration and metal fatigue.
4Stability of the object's composition
If locating pins are rigidly fixed to prevent any movement, then alignment stability is improved, but the pins cannot accommodate thermal expansion and stress variations during operation
Solution Approach 1:
The two-bore structure creates a dynamic accommodation system where the pin is held firmly in the first bore for alignment stability while the second bore (counterbore) provides a stress-relief zone. This stepped geometry allows the pin structure to maintain stable alignment while accommodating thermal expansion and stress variations through the differentiated bore structure, preventing rigid constraint that would lead to failure.
Solution Approach 2:
The second bore proximate to the mating surface provides beforehand cushioning by creating a stress-distributing geometry that accommodates thermal expansion and stress variations. This pre-designed stress-relief structure allows the locating pin system to maintain alignment stability while adapting to operational conditions without requiring rigid fixed constraints.
Data Source
AI summary
A fuel injector assembly has a control valve body and a plurality of end caps. End cap locating holes are formed into a mating surface of each end cap, and control valve body locating holes are formed into each mating surface of the control valve body. Locating pins inserted into the end cap and control valve body locating holes each have a fixed portion that affixes the locating pins to either the control valve body or the end cap. In the event of failure of a locating pin between the fixed portion and a free portion of the pins, the free portion maintains alignment of the control valve body locating holes with the end cap locating holes.