Fuel Pump Seal Wear Reduction via Axial Constraint and Damping

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Solution Overview

Problem

High-pressure fuel pumps for direct injection systems face issues with the short lifespan and high wear of seals around the piston, leading to fuel leakage and loss of sealing capability.

Innovation Solution

A fuel pump design with a collecting chamber and an annular seal positioned beneath the piston, where the axial dimension of the seat housing the seal is equal to or smaller than the seal itself, preventing axial movement and stress on the seal, and a damper device to reduce fuel flow pulsations, enhancing seal longevity and fuel delivery stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an annular seal is placed beneath the collecting chamber to prevent fuel leakage, then sealing capability is improved, but the seal is subject to high stress and wears out quickly

Engineering Contradiction:

Improvesealing capabilityVSAvoidseal lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent introduces a damper device as an intermediary element between the fuel supply system and the collecting chamber. This damper device absorbs fuel pulsations and reduces pressure oscillations, thereby reducing the stress on the annular seal. The damper acts as a mediator that protects the seal from direct exposure to high-stress fuel flow conditions, extending its operational life while maintaining sealing capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The damper device is positioned beforehand in the fuel supply line to cushion and dampen fuel pulsations before they reach the collecting chamber and the annular seal. This prior cushioning action prevents high-stress conditions from developing at the seal location, thereby preventing premature wear and extending the seal's lifespan while maintaining its sealing function.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Productivity

If the piston is allowed to move freely in the pumping chamber, then pumping efficiency is improved, but axial movement of the piston causes stress on the seal

Engineering Contradiction:

Improvepumping efficiencyVSAvoidseal stress resistance

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The damper device serves as an intermediary that decouples the piston's axial movement from the seal's stress conditions. By absorbing and dampening pressure oscillations, the damper protects the seal from stress while allowing the piston to move freely for efficient pumping operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The damper device is positioned beforehand in the fuel supply line to cushion pressure oscillations before they reach the collecting chamber. This prior cushioning action prevents stress from being transmitted to the annular seal, allowing the piston to operate freely without compromising seal integrity.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If fuel flow is regulated to maintain constant pressure in the common rail, then system control is improved, but pressure oscillations in the feed line cause noise and potential damage

Engineering Contradiction:

Improvepressure control stabilityVSAvoidnoise and vibration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The damper device acts as an intermediary element in the fuel supply line that absorbs and dampens pressure oscillations and fuel pulsations. This intermediary action reduces noise and vibration while maintaining the pressure control stability achieved through flow regulation in the common rail system.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The damper device is positioned beforehand in the feed line to cushion and dampen pressure oscillations before they propagate to the common rail and cause noise or damage. This prior cushioning action maintains the beneficial pressure control while eliminating harmful vibrations and noise.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 design significantly extends the seal's lifespan by preventing axial movement and stress, reducing fuel leakage, and achieving a high reduction in fuel pulsations, potentially exceeding a 50% decrease in amplitude, thereby improving the pump's operational efficiency and reliability.

Implementation Method 1

a damper device to reduce fuel pulsations and enhance sealing efficiency

Methodology Applied

Scientific EffectDamping: Damping

Data Source

PatentUS8556602B2Fuel pump with reduced seal wear for a direct injection system

Publication Date: 2013.10.15 MARELLI EURO SPA

AI summary

A fuel pump for a direct injection system comprises at least one pumping chamber, a piston slidingly mounted inside the pumping chamber to cyclically vary volume thereof, an intake duct connected to the pumping chamber and regulated by an inlet valve, a delivery duct connected to the pumping chamber and regulated by a one-way valve that allows only outgoing-fuel flow from the pumping chamber, a seat arranged below the pumping chamber around a lower portion of the piston, an annular seal housed in the seat and preventing fuel leakage along a side wall of the piston, and an annular element that delimits, on an upper side thereof, the seat housing the seal such that an axial dimension of the seat is not greater than an axial dimension of the seal to prevent the seal from axially “shaking” inside the seat as a consequence of cyclic axial movement of the piston.