Rocket Engine Nozzle Needle Pneumatic Thrust Control

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Solution Overview

Problem

Current rocket engine control systems for interceptor missiles face challenges in achieving precise and rapid thrust adjustments due to limitations in nozzle needle displacement mechanisms, which affect the agility and accuracy of course corrections for high-speed, unpredictably moving ballistic targets.

Innovation Solution

The engine device incorporates a pneumatic control system with a gas-fillable equalization and control chamber, where a nozzle needle is axially displaced by adjusting gas pressures in these chambers, allowing for precise and quick variation of the nozzle outlet cross-section, enabling continuous thrust adjustment from zero to maximum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a nozzle needle is mechanically displaced in the axial direction to regulate thrust, then the effective cross-section of the nozzle is reduced, but the positioning time is extended and thrust adjustment speed is reduced

Engineering Contradiction:
Improvethrust adjustment precisionVSAvoidnozzle needle positioning time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies pneumatic principles by introducing a control chamber filled with gas that acts on the nozzle needle. The gas pressure in the control chamber can be rapidly adjusted to move the nozzle needle axially, replacing slow mechanical displacement mechanisms with fast pneumatic actuation. This allows precise thrust regulation while achieving rapid positioning responses.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent changes the physical state parameter of the control system by using gas pressure instead of mechanical force. By varying the gas pressure in the control chamber, the nozzle needle position is quickly adjusted. This parameter change from mechanical to pneumatic control enables both precision and speed in thrust adjustment.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If discrete thrust pulses are used for course correction, then the control system is simple, but the thrust adjustment precision is insufficient for high-speed targets

Engineering Contradiction:
Improvecontrol system complexityVSAvoidthrust adjustment precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent transitions from static discrete thrust pulses to dynamic continuous thrust control. The pneumatic control chamber allows continuous adjustment of gas pressure, enabling the nozzle needle to be positioned at any point along its travel. This dynamic control capability provides precise thrust modulation while maintaining relatively simple system architecture.

Inventive Principle:
Principle #15Dynamics

3Productivity

If continuous thrust control with rapid nozzle needle displacement is implemented, then thrust adjustment precision is improved, but the gas pressure changes required are large and complex

Engineering Contradiction:
Improvethrust adjustment speedVSAvoidgas pressure control complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent introduces a control chamber as an intermediary between the control system and the nozzle needle. This intermediary chamber buffers and amplifies small gas pressure changes into significant nozzle needle displacements. The control chamber acts as a mediator that translates minimal pressure adjustments into rapid, precise needle movement, reducing the complexity of the overall pressure control system.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 precise and rapid thrust control, allowing for agile course corrections and improved missile guidance by varying the nozzle needle's position with short positioning times and minimal gas pressure changes, enhancing the missile's ability to intercept high-speed targets.

Implementation Method 1

A first section of the piston device is arranged in the compensation chamber and is pressurized by a gas in the compensation chamber in such a way that the nozzle needle experiences an axial force in the direction of the gas outlet opening. A second section of the piston device is arranged in the control chamber and can be pressurized by filling a gas into the control chamber in such a way that the nozzle needle experiences an axial force in the direction away from the gas outlet opening.

Methodology Applied
Scientific EffectGas pressure: Pressure Increase

Data Source

PatentEP3293389B1Engine device of a rocket engine
Publication Date: 2021.02.24 MBDA DEUTSCHIAND GMBH
  • EP3293389B1 patent drawingFigure 1
  • EP3293389B1 patent drawingFigure 2
  • EP3293389B1 patent drawingFigure 3

AI summary

An engine assembly (100) of a rocket engine, comprising an afterburner chamber (1), wherein the afterburner chamber (1) includes a gas inlet opening (27) for gas flowing into the afterburner chamber (1) and a gas outlet opening (20) for gas flowing out. The engine assembly further comprises a gas-fillable compensation chamber (3), a gas-fillable control chamber (2), and a nozzle needle (4), which is axially displaceable such that a first end region (28) of the nozzle needle (4) can be inserted at least partially into the gas outlet opening (20).The nozzle needle (4) has a piston assembly (5) at a second end region, wherein a first section (29) of the piston assembly (5) is arranged in the compensation chamber (3) and can be pressurized by a gas located in the compensation chamber (3) such that the nozzle needle (4) experiences an axial force in the direction of the gas outlet opening (20), and wherein a second section (7) of the piston assembly (5) is arranged in the control chamber (2) and can be pressurized by filling a gas into the control chamber (2) such that the nozzle needle (4) experiences an axial force in the direction away from the gas outlet opening (20).