Retractable Rocket Motor Igniter with Pressure Compensation
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Solution Overview
Problem
Existing rocket engine igniters are complex, leading to high manufacturing costs and reliability issues due to their numerous components, which can fail and are prone to thermal stress.
Innovation Solution
A rocket engine igniter with a movable spark plug and a pressure compensation chamber having two internal cavities separated by a movable base, where the spark plug is integral with the base, allowing pressure differences to drive the spark plug between deployed and stowed positions, reducing thermal stress and simplifying the structural configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of components are used in the igniter system, then the functionality and reliability can be improved, but the device complexity increases and manufacturing cost increases
Solution Approach 1:
The patent merges the spark plug and intermediate device into a single integrated component. The spark plug is positioned within the intermediate device housing, eliminating the need for separate mounting brackets, fasteners, and alignment mechanisms. This integration reduces the total component count while maintaining the functional separation between the electrical ignition source and the combustion initiation zone.
Solution Approach 2:
The intermediate device housing serves multiple functions simultaneously: it provides thermal isolation for the spark plug, contains the propellant injection system, and acts as the combustion initiation chamber. This multi-functionality eliminates the need for separate structural components, reducing overall system complexity while improving reliability through fewer potential failure points.
2Productivity
If the spark plug remains in the combustion chamber during operation, then combustion initiation is effective, but thermal stresses degrade the spark plug performance
Solution Approach 1:
The spark plug is designed to be movable relative to the combustion chamber, transitioning between a deployed position during combustion initiation and a retracted position during operation. This dynamic positioning allows the spark plug to be exposed to high temperatures only during the brief ignition phase, then withdrawn to a cooler zone, thereby maintaining both ignition effectiveness and component durability.
Solution Approach 2:
The spark plug is positioned in advance within the intermediate device before combustion begins. This preliminary positioning ensures that the spark plug is ready to initiate combustion immediately when triggered, while the intermediate device structure is already in place to provide thermal isolation and protect the spark plug from sustained thermal exposure.
3Object-affected harmful factors
If an intermediate device is used to isolate the spark plug, then thermal stress protection is achieved, but the number of components increases
Solution Approach 1:
The thermal isolation function is merged into the intermediate device housing structure itself, which is made of thermally resistant material and designed to physically separate the spark plug from the combustion chamber. This integration eliminates the need for separate thermal insulation layers or protective shields, reducing component count while maintaining effective thermal stress protection.
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 solution enables the spark plug to be in a position suitable for initiating combustion while being protected from thermal stresses, allowing repeated on/off operation of the rocket motor with reduced risk of degradation, and ensures proper propellant ignition by adjusting the pressure difference threshold.
Implementation Method 1
the base is movable within the compensation chamber as a function of the pressure difference between the first vent and the second vent. Depending on this pressure difference, the base takes different positions, thus driving the spark plug between the deployed position and the retracted position.
Implementation Method 2
When the rocket engine is ignited, the combustion of the propellants generates hot gases which cause an increase in pressure within the combustion chamber
Implementation Method 3
the combustion of the propellants generates hot gases which cause an increase in pressure within the combustion chamber
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
The invention relates to a rocket motor igniter (10), characterized in that it includes a spark plug (12), movable between a stowed position and a deployed position, and a pressure compensation chamber (14) having a first inner cavity (14A) and a second inner cavity (14B) separate from the first cavity. The first cavity and the second cavity are separated by at least one movable base (16). The spark plug is secured to the movable base. The first cavity is in communication with a first vent hole (22) while the second cavity is in communication with a second vent hole (24) separate from the first vent hole.