High-Pressure Pump Coil Spring Load Center Configuration
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Solution Overview
Problem
Conventional high-pressure pumps experience uneven wear and burnout between the plunger and cylinder due to oil film breakage at specific sliding interfaces, leading to reduced surface pressure and increased load on the plunger.
Innovation Solution
The high-pressure pump design incorporates a coil spring with a specific load center configuration, where the upper and lower load centers move in opposite directions along the coil spring circumference, causing the plunger to tilt and maintain a continuous oil film between the plunger and cylinder, preventing specific portions from sliding and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If gaps are provided between the retainer and plunger and between the tappet and plunger to reduce surface pressure, then load on the plunger is reduced, but oil film breakage occurs at specific portions causing uneven wear and burnout
Solution Approach 1:
The coil spring is designed with asymmetric winding directions where the upper half winds in one direction and the lower half winds in the opposite direction. This asymmetry creates alternating radial forces that prevent the plunger from tilting in a fixed direction, ensuring uniform contact and oil film distribution across the sliding interface, thereby preventing localized wear and burnout while maintaining reduced load through the gaps
2Device complexity
If only a specific portion of the sliding interface slides during plunger reciprocation, then the mechanism is simpler, but oil film breakage occurs causing uneven wear and burnout
Solution Approach 1:
The coil spring generates periodic radial forces that alternate in direction as the plunger reciprocates. The asymmetric winding configuration ensures that during each stroke cycle, the radial force direction reverses, causing different portions of the sliding interface to contact sequentially. This periodic variation in contact location prevents continuous sliding at a single spot, maintaining oil film integrity while keeping the sliding interface configuration simple
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 configuration effectively prevents uneven wear and burnout by ensuring a continuous oil film and balanced load distribution, enhancing the durability and performance of the pump.
Implementation Method 1
The coil spring is formed of a wire wound in a coil shape and disposed radially outward of another end of the plunger. The coil spring urges the other end of the plunger away from the pressurizing chamber and is capable of pressing the other end of the plunger against a cam of a driven shaft of the internal combustion engine.
Implementation Method 2
a size of a gap between the outer wall of the plunger and the inner wall of the cylinder cylindrical portion changes continuously, and an oil film is always formed in the gap. Therefore, uneven wear and burnout between the plunger and the cylinder can be reduced.
Data Source
AI summary
In a high-pressure pump, a center of load in a virtual plane including an end face of a coil spring facing a pressurizing chamber in an axial direction is defined as an upper load center, and a center of load in a virtual plane including an end face of the coil spring facing a cam in the axial direction is defined as a lower load center. The coil spring is configured such that, when viewed in the axial direction, during motion of a plunger toward the pressurizing chamber by rotation of the cam, the upper load center moves in one direction along a circumference of the coil spring while the lower load center moves in an opposite direction along the circumference of the coil spring, and the lower load center substantially coincides with the upper load center and subsequently further moves in the opposite direction.