Fuel Injection Device Annular Positioning Member Alignment
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Solution Overview
Problem
Existing fuel injection devices face accuracy and stability issues due to dislocation between the nozzle body and the orifice member, leading to variations in fuel injection characteristics, which affect performance and productivity.
Innovation Solution
A fuel injection device is designed with an annular positioning member that accurately sets the radial locations of the valve body and housing member, using a stepped surface and return spring configuration to ensure proper alignment and stability, thereby maintaining consistent fuel injection characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If alignment pins are used to position components, then component positioning is achieved, but positioning accuracy deteriorates due to hole portion and pin size errors
Solution Approach 1:
A positioning member with a positioning surface is introduced as an intermediary between the nozzle body and orifice member. The positioning surface fits into a positioning groove, providing a stable reference that eliminates the need for multiple alignment pins and their associated hole portions, thereby resolving the contradiction between ease of positioning and positioning accuracy
Solution Approach 2:
The invention extracts and eliminates the alignment pins and their associated hole portions from the assembly. By removing these error-prone elements and replacing them with a positioning member that integrates the positioning function directly into the orifice member structure, the source of positioning errors is removed while maintaining positioning capability
2Ease of manufacture
If multiple components are assembled with pins, then assembly is achieved, but assembly time increases due to positioning errors requiring adjustment
Solution Approach 1:
The positioning groove and positioning surface are designed in advance during the manufacturing process, with precise dimensions and tolerances built into the tooling. This preliminary action ensures that when components are assembled, they automatically align correctly without requiring post-assembly adjustments or rework, thereby increasing assembly speed
Solution Approach 2:
The positioning member acts as a mediator that guides the orifice member into correct alignment with the nozzle body during assembly. This intermediary component simplifies the assembly process by providing self-alignment, eliminating the need for manual positioning adjustments and reducing assembly time
3Device complexity
If component positioning is not precise, then assembly is simpler, but fuel injection characteristic stability deteriorates
Solution Approach 1:
The positioning member with its precisely engineered positioning surface and groove geometry serves as a mediator that ensures accurate relative positioning between the nozzle body and orifice member. This intermediary structure guarantees consistent fuel passage alignment and injection hole positioning, maintaining fuel injection characteristic stability while keeping the assembly process simple
Solution Approach 2:
The invention addresses positioning in a different dimensional approach by using a fitting relationship between the positioning surface and positioning groove, rather than relying on multiple pin-point contacts. This dimensional change from point contacts to surface engagement provides more stable and repeatable positioning, ensuring fuel injection reliability
Data Source
AI summary
A fuel injection device includes a cylinder defining a pressure chamber at an end portion of a nozzle needle. In the cylinder, a floating plate is provided as a controlling member of fuel pressure. An orifice member and a nozzle body are lined by an annular positioning member, using a circular peripheral surface of the orifice member and a circular peripheral surface of the nozzle body as a reference surface. Thereby, radial locations of the nozzle body and the orifice member are defined. Furthermore, a location of the floating plate is defined by the nozzle body with the nozzle needle. Therefore, the floating plate can be located to a proper location relative to the orifice member.