Decoupled Spring Seat for Diesel Plunger Self-Centering
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Solution Overview
Problem
The existing pumping assembly for high pressure diesel fuel pumps experiences wear and potential seizure due to radial spring force and side loads applied to the plunger, resulting from contact between the spring seat and the plunger.
Innovation Solution
A pumping assembly design that includes a shoulder member coupled to the plunger and a spring seat member with a radial section and an axial section, where the spring seat member is decoupled from the plunger, allowing the plunger to self-center and reducing side loads by stabilizing the shoe and reestablishing a fluid film around the plunger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spring seat is rigidly mounted on the plunger to maintain contact between the roller and cam lobe, then the plunger return spring can maintain contact forces, but radial spring force causes wear and potential seizure of the plunger
Solution Approach 1:
The spring seat is divided into two functional sections: an axial section that contacts the shoe and transfers axial forces, and a radial section that contacts the plunger and absorbs radial forces. This segmentation allows the spring seat to handle radial spring forces without transmitting them to the plunger, thereby preventing wear and seizure while maintaining reliable contact between the roller and cam lobe.
Solution Approach 2:
The spring seat acts as an intermediary component between the plunger and the plunger return spring. By positioning the radial section of the spring seat against the plunger and the axial section against the shoe, it mediates the force transmission, allowing the spring forces to be absorbed and transferred without directly loading the plunger with radial forces.
2Stability of the object's composition
If the spring seat acts as a guide for the spring to maintain concentricity, then the spring remains properly aligned, but the plunger experiences side loads during filling and pumping strokes
Solution Approach 1:
The spring seat is segmented into axial and radial sections, each handling specific force components. The radial section maintains spring concentricity by guiding the spring, while the axial section transfers axial forces to the shoe. This segmentation prevents side loads from being transmitted to the plunger during filling and pumping strokes.
Solution Approach 2:
The spring seat serves as an intermediary that decouples the guiding function from the force transmission function. By positioning the radial section to guide the spring and the axial section to transfer forces to the shoe, it mediates between the spring and plunger, eliminating side loads on the plunger while maintaining spring stability.
3Power
If the spring forces are transferred through the spring seat and plunger assembly, then the plunger experiences axial and radial forces during operation, but this causes wear and possible seizure
Solution Approach 1:
The spring seat is segmented into radial and axial sections that separately handle different force components. The radial section absorbs radial spring forces, while the axial section transfers axial forces to the shoe. This segmentation prevents both axial and radial forces from being transmitted to the plunger, eliminating wear and seizure risks while maintaining necessary force transfer for power transmission.
Solution Approach 2:
The spring seat acts as an intermediary force transfer mechanism between the plunger return spring and the shoe. By positioning its radial section against the plunger and axial section against the shoe, it mediates force transmission, allowing power to be transferred through the system without subjecting the plunger to harmful radial and axial forces that cause wear and seizure.
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 mitigates wear and seizure by reducing side loads and allowing the plunger to self-center, ensuring proper fluid flow and reducing contact stress during filling strokes.
Implementation Method 1
a plunger return spring (6) located in a spring chamber (8). Rotation of a cam lobe (80) of a driveshaft assembly causes force to be transferred to the plunger (4) via a roller (14) and a shoe (12)
Implementation Method 2
Rotation of a cam lobe (80) of a driveshaft assembly causes force to be transferred to the plunger (4) via a roller (14) and a shoe (12), thereby causing the plunger (4) to move in a reciprocating motion
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A pumping assembly for a high pressure diesel fuel pump comprises a spring seat member (120) against which a plunger return spring (106) abuts, and a shoulder member (140) which is coupled to the plunger (104); wherein the plunger (104) protrudes through a clearance through hole (134) of the spring seat member (140) such that the plunger is decoupled from the spring seat member (120) so that spring forces do not act on the plunger (104) and it is able to self-centre during operation of the pump. The pumping assembly further comprises a shoe (112), a top face (164) of which being non-orthogonal to a pumping axis (A).