High-Pressure Fuel Pump Cylinder Fixing to Prevent Plunger Sticking
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Solution Overview
Problem
High-pressure fuel pumps face increased costs due to the need for specialized facilities for ring mash bonding and risk of plunger sticking due to radial displacement of the cylinder, which can lead to contact and sticking issues as fuel pressure increases.
Innovation Solution
A high-pressure fuel pump design where the cylinder is swaged into a hole in the pump body using a convex portion or screw thread, with a radial clearance from the bonding portion to the upper end to prevent radial displacement and sticking, allowing for simple assembly and reduced radial movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ring mash bonding is used to fix the cylinder to the pump body, then the cylinder is securely fixed, but specialized facilities and increased manufacturing costs are required
Solution Approach 1:
The invention extracts the cylinder from the press contact bonding process and replaces it with a snap-fit structure where the cylindrical portion elastically deforms to engage with the pump body, eliminating the need for specialized bonding facilities while maintaining secure fixation
Solution Approach 2:
The invention replaces the thermal-mechanical bonding process (ring mash bonding) with a purely mechanical snap-fit mechanism utilizing elastic deformation of the cylindrical portion, simplifying the manufacturing process and eliminating specialized facility requirements
2Stress or pressure
If the cylinder is fixed near the pressing chamber to withstand high fuel pressure, then high pressure capability is improved, but radial displacement causes the plunger to stick
Solution Approach 1:
The invention applies different structural characteristics to different portions of the cylinder: the lower end has a larger outer diameter for secure engagement with the pump body to withstand high pressure, while the upper end maintains a smaller outer diameter with clearance from the pump body to prevent radial displacement and plunger sticking
Solution Approach 2:
The cylinder is segmented into functional zones: a lower engagement portion that provides structural support and pressure resistance, and an upper operational portion that maintains clearance to prevent sticking, allowing each segment to optimize its function independently
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 design effectively fixes the cylinder to the pump body using a simple structure, reducing radial displacement and preventing plunger sticking, thus ensuring reliable operation at high fuel pressures.
Implementation Method 1
a cylindrical portion 6d, which has a smaller outer diameter than the outer diameter of a large diameter portion 6c and is elastically deformed in a radial direction to snap to the pump body 1
Data Source
AI summary
Provided is a high-pressure fuel pump which can fix a cylinder to a pump body using a simple structure, and can reduce a displacement amount inward in a radial direction of the cylinder. A high-pressure fuel pump includes a pump body which is formed with a pressing chamber and a cylinder which is inserted in a hole formed in the pump body. The cylinder is swaged to the hole by pressing a convex portion on an outside in a radial direction to fit into the hole on an opposite side to the pressing chamber, by screwing a formed screw thread into the hole, or by being swaged with the opposite side to the pressing chamber. The cylinder is formed with a clearance in the radial direction with respect to the hole of the pump body all over a region from a bonding portion to an upper end.