Quantity-Limiting Valve Underflow Structure for Injection Timing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional quantity-limiting valves for internal combustion engine injection systems experience delayed and abrupt piston release from their seat, leading to an opening wave in pressure profiles, which causes incorrect evaluation of the start of injection and potential engine damage due to excessive fuel supply.

Innovation Solution

The introduction of an underflow structure with projections or recesses that allow fuel to flow into an intermediate space between the piston and the stop element, creating a larger pressure-loaded surface area for quicker piston release and a smoother transition, thereby avoiding the formation of opening waves and ensuring accurate pressure profile evaluation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the piston is prestressed against the stop surface in the first functional position, then the valve maintains its position and prevents fuel flow, but the piston releases belatedly and abruptly when injection starts, causing an opening wave in the pressure profile

Engineering Contradiction:

Improveposition stabilityVSAvoidpressure profile evaluation accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The stop surface is segmented into multiple regions: a first region with a first friction coefficient and a second region with a second friction coefficient. This segmentation allows different portions of the piston end face to experience different friction forces during movement, enabling controlled transition from the first functional position to the second functional position without abrupt release.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the stop surface are assigned different friction coefficients to achieve local quality variation. The first region provides higher friction to maintain position stability during normal operation, while the second region provides lower friction to facilitate smooth piston release when injection starts, thereby eliminating the opening wave phenomenon.

Inventive Principle:

Principle #3Local quality

2Reliability

If the piston is held firmly against the stop surface, then the valve prevents excessive fuel supply, but the abrupt release causes an opening wave that leads to incorrect injection start determination

Engineering Contradiction:

Improvefuel supply controlVSAvoidinjection timing accuracy

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The stop surface is divided into regions with different friction characteristics, allowing the piston to be held firmly in the first functional position during normal operation while enabling a controlled, gradual release when injection starts. This segmentation prevents the abrupt release that causes timing errors.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The friction coefficient between the piston and stop surface is made dynamically variable through the different friction regions. During normal operation, the higher friction region maintains firm holding, while during injection start, the piston transitions to the lower friction region for smooth release, optimizing both fuel control and timing accuracy.

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

This solution enables a gentle and continuous piston movement, preventing the formation of opening waves and allowing for reliable, error-free evaluation of the injection start, maintaining consistent response behavior over the valve's service life without disrupting pressure profiles.

Implementation Method 1

a pressure difference develops across the piston between the inflow area and the outflow area. Due to the pressure difference, the piston is released from the stop surface and moved into the outflow area

Methodology Applied

Scientific EffectPressure difference: Pressure Gradient

Implementation Method 2

The piston is prestressed with an end face against a stop surface of a stop element by a spring element

Methodology Applied

Scientific EffectElastic force: Spring

Implementation Method 3

fuel continues to flow from the inflow area via the fluid connection into the outflow area, with the pressure difference being increasingly equalized

Methodology Applied

Scientific EffectPressure-driven flow: Pressure Gradient

Data Source

PatentEP3008327B1Quantity-limiting valve

Publication Date: 2018.05.23 ROLLS ROYCE SOLUTIONS GMBH

Figure 1~2B
Figure 3

AI summary

The invention relates to a quantity-limiting valve (1) for an injection system (6) of an internal combustion engine (8), comprising an inflow region (7), an outflow region (9), and a piston (13) which is movably guided in a cylinder (11) and by means of which the inflow region (7) is separated from the outflow region (9). The inflow region (7) and the outflow region (9) are fluidically connected via an overflow channel (15) which passes through some areas of the piston (13) and via a current path (17) arranged between a circumferential surface (19) of the piston (13) and an inner surface (21) of the cylinder (11). An end surface (25) of the piston (13) is preloaded against a stop surface (27) of a stop element (29) in a first functional position. An underflow structure (39) is formed in a region where the end surface (25) contacts the stop surface (27) in the first functional position, said underflow structure comprising at least one intermediate area (41), which is fluidically connected to the inflow region (7), between the piston (11) and the stop element (29).