Pressure-Compensated Injector Actuator Sealing Diameter Optimization

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Solution Overview

Problem

Injectors with pressure-balanced control valves experience significant changes in opening and closing behavior due to wear over their service life, leading to a pressure step that affects the injector's performance.

Innovation Solution

The sealing diameter of the actuator is maintained at less than 3 mm to minimize wear-related effects, ensuring a small pressure step area and moderate compressive forces, allowing for low-power actuators with reduced installation space requirements and lower wear on components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the sealing diameter of the actuator is increased to handle higher fuel pressures, then the pressure force acting on the actuator increases, but the area of wear increases quadratically leading to significant changes in opening and closing behavior over service life

Engineering Contradiction:
Improvepressure forceVSAvoidopening and closing behavior consistency
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The patent applies parameter changes by selecting a specific sealing diameter range (less than 3 mm, preferably 2.5-2.95 mm, or 2.0-2.5 mm) that optimizes the balance between handling sufficient fuel pressure and minimizing wear-related performance degradation. This parameter optimization ensures that the pressure force remains adequate while the wear area stays small enough to maintain consistent opening and closing behavior throughout the injector's service life.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the sealing diameter of the actuator is reduced to minimize wear effects, then the pressure force acting on the actuator decreases, but the ability to handle high fuel pressures is compromised

Engineering Contradiction:
Improveopening and closing behavior consistencyVSAvoidpressure force
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The patent resolves this contradiction by precisely defining an optimal sealing diameter parameter range (less than 3 mm, with preferred sub-ranges of 2.5-2.95 mm and 2.0-2.5 mm). This parameter selection ensures that the sealing diameter is small enough to minimize wear area and maintain consistent opening/closing behavior, while still being large enough to generate sufficient pressure force for handling high fuel pressures throughout the injector's service life.

Inventive Principle:
Principle #35Parameter changes

3Force

If a larger actuator is used to handle high fuel pressures, then the pressure force is sufficient, but the weight of the actuator increases requiring higher power actuators with greater installation space

Engineering Contradiction:
Improvepressure forceVSAvoidactuator weight
Core Design Contradiction:
ForceVSWeight of moving object

Solution Approach 1:

The patent applies parameter changes by optimizing the sealing diameter to be less than 3 mm (with preferred ranges of 2.5-2.95 mm and 2.0-2.5 mm). This reduced diameter directly decreases the actuator's mass and weight, allowing the use of lower-power actuators with reduced installation space requirements while still generating sufficient pressure force to handle high fuel pressures throughout the injector's operational life.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2156044B1Injector having a pressure-compensated control valve
Publication Date: 2012.10.31 ROBERT BOSCH GMBH
  • EP2156044B1 patent drawingFigure 1~2
  • EP2156044B1 patent drawingFigure 3~4

AI summary

The invention relates to an injector for injecting fuel into a combustion chamber of an internal combustion engine, particularly a common rail injector, comprising a valve element (2), which can be switched from a closed position to an open position in which it releases the fuel flow into the combustion chamber, and a control valve (10) that is at least approximately pressure-compensated in the axial direction, having an actuating element (12) adjustable on a valve seat (16). According to the invention, a sealing diameter of the actuating element resting against the valve seat is less than 3 mm.