High-Pressure Fuel Pump Weld Joint Geometry for Stress and Spatter Control
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Solution Overview
Problem
Existing high-pressure fuel supply pumps face challenges in increasing the strength of the welding portion between the discharge joint and the pump body due to stress concentration at the annular recess shape, which is exacerbated by higher fuel pressures, and are limited by the difficulty in further increasing the curvature radius to prevent spatter entry.
Innovation Solution
A high-pressure fuel supply pump design with a functional component featuring a gap and concave curved surface extending from the welding portion to the pump body's facing surface, forming a space that reduces stress concentration while preventing spatter entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the curvature radius of the annular recess shape is increased to reduce stress concentration, then the stress on the pump body is reduced, but the ability to prevent spatter from entering the pump body is compromised
Solution Approach 1:
The hole structure is segmented into three distinct regions: an annular recess shape at the opening for spatter prevention, a transition curved surface in the middle for stress reduction, and a straight peripheral surface for structural support. This segmentation allows each region to fulfill its specific function without compromising the others.
Solution Approach 2:
Different regions of the hole are given different geometric properties tailored to their specific functions: the annular recess at the opening provides sharp edges for spatter blocking, while the transition curved surface provides gradual curvature for stress reduction, and the straight peripheral surface provides structural rigidity.
2Productivity
If the fuel pressure is increased to improve fuel efficiency, then the fuel efficiency is improved, but the stress on the welding portion and pump body increases
Solution Approach 1:
A transition curved surface is introduced between the annular recess and the straight peripheral surface. This curved transition eliminates sharp corners and distributes stress more evenly, preventing stress concentration that would occur at abrupt geometric changes, thereby maintaining welding portion strength under high fuel pressure.
3Reliability
If the inner peripheral portion of the hole and the outer peripheral portion of the discharge joint are brought into contact on the deep side to prevent spatter entry, then spatter prevention is improved, but the curvature radius of the annular recess cannot be increased further
Solution Approach 1:
The hole structure is segmented into three distinct regions: an annular recess shape at the opening for spatter prevention, a transition curved surface in the middle for stress reduction, and a straight peripheral surface for structural support. This segmentation allows each region to fulfill its specific function without compromising the others.
Solution Approach 2:
A transition curved surface is introduced between the annular recess and the straight peripheral surface. This curved transition eliminates sharp corners and distributes stress more evenly, preventing stress concentration that would occur at abrupt geometric changes, thereby maintaining welding portion strength under high fuel pressure.
Data Source
Figure 1
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AI summary
Provided is a high-pressure fuel supply pump capable of reducing stress generated in a portion forming a space provided for a welding portion while preventing spatter from entering the pump. In a high-pressure fuel supply pump 1, a discharge joint 19 is attached to an attachment hole 1h provided in a pump body 1a via a welding portion 90. A space portion 91 is formed from a terminal end portion 90b of the welding portion 90 toward a deep side of the attachment hole 1h. The discharge joint has an end surface 71 of the attachment hole 1h in the depth direction and an outer peripheral surface 72 rising from the end surface 71. The wall surface of the attachment hole 1h has a facing surface 81 facing the end surface 71 and an inner peripheral surface 82 located outside the outer peripheral surface 72 and extending from the facing surface 81 to the terminal end portion 90b of the welding portion. The end surface 71 and the facing surface 81 form a gap C in a predetermined range. The space portion 91 is formed from the terminal end portion 90b of the welding portion to the facing surface 81. The entire inner peripheral surface 82 from the terminal end portion 90b of the welding portion to the facing surface 81 is formed as a concave curved surface to constitute a wall surface of the space portion 91.