Flexible Crescent for Diesel Fuel Pump Back Leakage

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Low-pressure fuel pumps in diesel engines experience radial back leakage due to fuel flowing backwards through gaps between gear teeth and the crescent member, leading to reduced engine performance and increased heat and wear, which is costly to mitigate through precise machining.

Innovation Solution

A flexible crescent member is designed to maintain constant contact with gear teeth, featuring a gap for heat dissipation and absorption, and is resilient to reduce wear and backflow, allowing it to flex and absorb friction-generated heat while preventing unwanted fluid flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If machining precision is increased to reduce back leakage, then back leakage is reduced, but manufacturing cost increases

Engineering Contradiction:

Improveback leakage reductionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs a flexible crescent member made of elastomeric material that conforms to the gear teeth surfaces, creating an effective seal without requiring high-precision machining of the pump housing and gears. The flexibility allows the crescent to adapt to manufacturing tolerances while maintaining sealing effectiveness, thus reducing back leakage without increasing manufacturing costs.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The invention changes the material parameter from rigid metal to flexible elastomeric material for the crescent member. This parameter change allows the sealing surface to deform and conform to the gear teeth, compensating for manufacturing imperfections and reducing back leakage without requiring tighter machining tolerances.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If metal-to-metal contact is increased to improve sealing, then sealing improves, but heat generation and wear increase

Engineering Contradiction:

Improvesealing performanceVSAvoidheat generation

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The flexible elastomeric crescent member creates sealing contact with the gear teeth through its compliance rather than rigid metal-to-metal contact. This flexible contact achieves effective sealing while allowing for thermal expansion and reducing heat generation, as the elastomeric material can deform to maintain contact without the friction and heat associated with rigid metal surfaces.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The invention uses composite material properties by combining the structural support of a rigid framework with the sealing properties of flexible elastomeric material. This composite approach allows the crescent to maintain sealing contact while the elastomeric surface reduces friction and heat generation compared to pure metal contact.

Inventive Principle:

Principle #40Composite materials

3Reliability

If rigid crescent member is used to maintain contact, then sealing is improved, but wear and friction welding increase

Engineering Contradiction:

Improvecontact consistencyVSAvoidservice life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The flexible elastomeric crescent member maintains consistent contact with the gear teeth through its ability to deform and conform to the rotating gears. This flexibility prevents the wear and friction welding problems associated with rigid metal-to-metal contact, as the elastomeric material can accommodate misalignments and surface irregularities without generating excessive friction or adhering to the metal surfaces.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The invention transitions from a static rigid crescent to a dynamic flexible crescent that can adapt its shape during operation. The flexible member dynamically conforms to the gear tooth surfaces as they rotate, maintaining sealing contact while reducing wear through its ability to absorb shocks and accommodate variations in gear geometry.

Inventive Principle:

Principle #15Dynamics

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 flexible crescent member effectively reduces back leakage and heat buildup, minimizing wear and maintaining performance across a range of operating speeds without the need for high-precision machining, thus enhancing engine efficiency and reducing costs.

Implementation Method 1

the crescent member comprises a gap to allow fluid to flow within the crescent member to absorb and dissipate the heat generated by friction

Methodology Applied

Scientific EffectHeat absorption: Absorption (physical)

Implementation Method 2

the crescent member comprises a gap to allow fluid to flow within the crescent member to absorb and dissipate the heat generated by friction

Methodology Applied

Scientific EffectHeat dissipation: Convection

Data Source

PatentUS12117003B2Flexible crescent for low pressure fuel pump

Publication Date: 2024.10.15 CUMMINS-SCANIA HPCR SYST LLC

AI summary

A crescent member is disclosed which is configured to be in constant contact with outer and inner gear teeth to prevent unwanted fluid backflow between the gears. The crescent member may be part of a low-pressure fuel pump system for a diesel engine. In order to reduce heat buildup in the crescent member and gear teeth, the crescent member comprises a gap to allow fluid to flow within the crescent member to absorb and dissipate the heat generated by friction. The crescent member is resilient to maintain constant contact, but flexible enough to reduce wear from friction over time.