Orifice Working Method for Fuel Injection Valves
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Solution Overview
Problem
Existing fuel injection valves face challenges in achieving high working accuracy and productivity due to the difficulty in managing the axial length of the orifice with high precision, leading to variations in injection amount and accumulation of soot, which can cause thick combustion and increased particulate matter.
Innovation Solution
A working method for an orifice that involves forming an orifice hole in an orifice forming member and then pressing the downstream end surface in a direction toward the upstream side using a punch with a cutting blade portion, causing the material to flow and form a cross-sectional area reduction portion, which reduces the orifice area from the upstream to the downstream side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the orifice is formed in a conical shape with multiple working steps, then the spray spread is improved, but the manufacturing precision deteriorates due to stacked dimensional and working errors
Solution Approach 1:
The orifice is divided into two distinct portions: a first portion (inlet side) with a first cross-sectional area and a second portion (outlet side) with a second cross-sectional area. This segmentation allows each portion to be formed with specific dimensional control, preventing the stacking of errors that would occur in a continuous conical shape formed by multiple working steps.
Solution Approach 2:
The invention changes the geometric parameters of the orifice by defining specific cross-sectional areas for the first and second portions rather than using a continuous taper. By controlling the cross-sectional areas and lengths of each portion independently, the manufacturing precision is improved while still achieving the desired spray characteristics.
2Device complexity
If the axial length of the orifice is not controlled with high accuracy, then the manufacturing complexity is reduced, but the injection amount varies
Solution Approach 1:
The invention shifts from controlling the axial length parameter to controlling the cross-sectional area parameter. By specifying the first cross-sectional area and second cross-sectional area, the design achieves reliable injection amounts without requiring high-precision control of axial dimensions, thereby reducing manufacturing complexity while maintaining reliability.
Solution Approach 2:
The invention replaces dimensional control (mechanical measurement of axial length) with area control. This substitution allows for easier manufacturing and measurement while achieving the same functional outcome of consistent injection amounts.
3Ease of manufacture
If the orifice has a conical shape tapered toward downstream side, then the spray distribution is improved, but the soot accumulation increases
Solution Approach 1:
The orifice is segmented into a first portion and a second portion with distinct cross-sectional areas. This segmentation creates a specific flow pattern that improves spray distribution while reducing the conditions that lead to soot accumulation, compared to a continuous conical shape.
Solution Approach 2:
Different portions of the orifice are given different cross-sectional areas to achieve local optimization. The first portion has a larger cross-sectional area to reduce velocity and prevent soot accumulation, while the second portion has a smaller cross-sectional area to maintain spray distribution quality.
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 method achieves excellent working accuracy and high productivity, allowing for the formation of a tapered portion on the entire circumference of the orifice inner wall, which helps in reducing the injection amount variations and minimizing soot accumulation, thereby improving fuel injection efficiency and reducing particulate matter.
Implementation Method 1
pressing a downstream end surface of the orifice forming member in which the orifice hole opens, in a direction toward an upstream side of the orifice hole by a punch having a cutting blade portion larger than a cross section of the orifice hole. The second step causes a material of the orifice forming member to flow from an entire circumference at a downstream end portion of the orifice hole to an inside of the orifice hole
Data Source
AI summary
An object of the present invention is to provide a working method of an orifice, which has excellent working accuracy and high productivity in order to work an inclination portion (tapered portion) on the entire circumference of an inner wall of an orifice. Therefore, a working method of an orifice includes a first step of forming an orifice hole 54d in an orifice forming member, a second step of pressing a downstream end surface of the orifice forming member in which the orifice hole 54d opens, in a direction toward an upstream side of the orifice hole 54d by a punch 46 having a cutting blade portion 46a larger than a cross section of the orifice hole 54d. The second step causes a material of the orifice forming member to flow from an entire circumference at the downstream end portion of the orifice hole 54d to an inside of the orifice hole 54d to form a cross-sectional area reduction portion 54s in which a cross-sectional area of the orifice hole 54d is reduced from an upstream side to a downstream side.