Variable Pitch Actuating Spring for Fuel Pump Piston Wear Reduction
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Solution Overview
Problem
High-pressure fuel pumps in direct injection systems face premature piston seizure due to excessive sliding friction, leading to reduced operating life and increased wear, which existing technologies have not adequately addressed.
Innovation Solution
A high-pressure fuel pump design featuring an actuating spring with a variable pitch between its turns, reducing lateral load and wear by altering the application direction of the spring's lateral load, thereby minimizing the risk of piston jamming and extending operational life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional actuating spring with constant pitch is used, then the spring provides consistent elastic force, but excessive lateral load causes piston seizure and reduced operating life
Solution Approach 1:
The spring pitch is made variable rather than uniform, creating local differences in turn spacing. Specifically, the pitch decreases in predetermined portions along the spring length, causing those sections to pack-tighten at different compression stages. This local variation in geometry redistributes the lateral load application, preventing excessive concentrated lateral forces on the piston while maintaining the spring's elastic function.
2Object-affected harmful factors
If the spring pitch is reduced to minimize lateral load, then piston wear is reduced, but the spring's ability to provide sufficient elastic force may be compromised
Solution Approach 1:
The spring's geometric parameter (pitch) is changed from constant to variable along its length. By strategically reducing the pitch in predetermined portions while maintaining or adjusting other spring parameters (such as wire diameter, total turns, or active turns), the spring achieves optimized lateral load distribution. This parameter variation allows the spring to provide sufficient elastic force for piston actuation while minimizing excessive lateral loads 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
The variable pitch actuating spring significantly reduces lateral load, minimizing piston wear and extending the operational life of the high-pressure fuel pump while maintaining simplicity and cost-effectiveness in production.
Implementation Method 1
an actuating spring (16) which has a plurality of turns and is coupled to the piston (15) so as to push the piston (15) towards a position of maximum volume or minimum volume of the pumping chamber (14). The actuating spring (16) has, along its length, a pitch (P) that is variable between the turns
Implementation Method 2
The actuating spring (16) has, along its length, a pitch (P) that is variable between the turns so that at each cycle of the piston (15) a predetermined portion of the turns that is less than all of the turns pack—tighten together so as to change the application direction of the lateral load generated by the actuating spring (16) for limiting the maximum value of lateral load
Data Source
AI summary
Fuel pump for a direct injection system provided with a common rail. The fuel pump has a pumping chamber defined in a main body; a piston which is mounted in a sliding manner inside the pumping chamber to cyclically vary the volume of the pumping chamber; an intake channel which originates from a wall of the pumping chamber; an intake valve which is coupled to the intake channel; a delivery channel which originates from a wall of the pumping chamber; a delivery valve which is coupled to the delivery channel; and an actuating spring which has a plurality of turns having a pitch that varies between the turns and that is coupled to the piston so as to push the piston towards a maximum volume or minimum volume position of the pumping chamber.